e-book science experiments(1)

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FUN & EASY SCIENCE PROJECTS: GRADES 7 & 8 VOLUME 4 | 60 science projects for grades 7 & 8 Revision 1.108 Senior Acquisitions Editor, Development Editor, Technical Editor, Production Editor, Copy Editor, Editorial Manager, Production Manager, Vice President and Executive Group Publisher, Vice President and Publisher, Book Designers, Compositor, Proof reader, Indexer, Project Coordinator, Cover Designer all by: JB Concepts design & media group, Inc. Int. Copyright 2010 No part of this electronic publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections certain sections of the International Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Centre. Requests to the Publisher for permission should be addressed to: Experiland Permissions Department, part of JB Concepts group, Pty (Ltd) online at http://www.experiland.com/ Limit of Liability/Disclaimer of Warranty: The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation warranties of fitness for a particular purpose. No warranty may be created or extended by sales or promotional materials. Neither the publisher nor the author shall be liable for damages arising here from. For general information on our other products and services or to obtain technical support, please contact our Customer Care Department @ [email protected] | JB Concepts | Experiland publishes its books in a variety of electronic formats. Several of the content that appears in this book is not available on our website. ERB110 8 0 5 TRADEMARKS: JB Concepts design & media, and the Experiland logo is trademarks or registered companies of JB Concepts group Pty (Ltd), and/or its affiliates, worldwide, and may not be used without written permission. All other trademarks are the property of their respective owners. JB Concepts group, Pty (Ltd) is not associated with any product or vendor mentioned in this book.

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PREFACE

ACKNOWLEDGEMENTS Little can be achieved in any field of human endeavour without the support, encouragement and

assistance of others. This book is no exception; it seemed a most formidable task when pen was

first put to paper. The science projects and experiments contained in this book have different

origins; most are original constructions, while some Golden Oldies have been carefully selected to

offer variety, encourage curiosity, and to challenge even the most accomplished young science

devotees capabilities.

Many thanks to everyone involved for verifying the many technical aspects of some of the projects;

the professionals who edited the manuscripts and made many valuable suggestions and the entire

Experiland team who coped with innumerable corrections and revisions!

FOREWORD Thank you for purchasing a science experiment e-book from Experiland.com! Whether you are a

parent or a student trying to find an idea for a science project, a teacher looking for ideas for the

classroom, or a science enthusiast who enjoys the delight of experimentation, we trust you will find

what you're looking for in this book. This book is a fascinating collection of both old and new

science projects & experiments covering the whole basic spectrum of the astonishing field of

science, and at the same time avoiding repetitions and similarities so often found in science project

literature.

This book is not intended for serious scientists, we will not be discussing quantum physics,

Astrophysical equations, or Human stem cell cyto-kinesis. Rather it is written and compiled as fun

educational entertainment for the young scientist who enjoys putting their mental agility to test

and curiosity to rest!

Enjoy the content and have many hours of fun with the experiments!

IMPORTANT DISCLAIMER: While Experiland.com makes every effort to provide science experiment & project ideas that are safe and fun for kids, it is every parents own responsibility to supervise their kids whilst performing these experiments and to choose only the experiments that they deem to be safe in their own homes. Experiland.com will not take any responsibility with regard to injuries, losses, damages, claims or any expenses arising out of or resulting from using our science experiments & project ideas on our website or in our e-books.

Copyright www.Experiland.com All rights reserved. Experiland.com is part of the JB Concepts design & media group

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LETS BEGIN!

INTRODUCTION

Greetings fellow scientists! Welcome to the exciting exploration of the world around us...the

world of science. This is a book full of fun & thought-provoking science projects and

experiments that will teach you, step-by-step, how to create an exciting project that not only

demonstrates good scientific practice but provides a safe and fun educational experience

too! With this book you will discover that science is a part of every object in our daily lives.

Who knows? Maybe someday you'll create your own fascinating inventionsor even grow

up to be a rocket scientist!

You can read all the books on music and guitars in the world, but that won't make you a great

guitar player. You have to actually practise with a guitar to get it right! It is easiest to figure

things out by getting your hands 'dirty' by doing! Science works exactly the same way. Yes,

you can learn a lot in science class or by doing homework, but there's nothing quite as much

fun as learning by getting your hands dirty doing some science experiments.

Science can be real simple and is actually only about understanding the world you live in!

Science certainly does not need to be complicated formulas, heavy text books and geeky

guys in white lab coats with thick glasses. Doing science experiments are all about testing

and getting results, even if you get a surprising result than you might not have expected. But

remember, even if things don't work out as you would have hoped, a good scientist is

constantly asking: Why? Science is in fact only an organized system created by people to

gather and store information. We use it as a way to define and understand the world we live

in!

Science experiments are an awesome part of science that allows you to engage in cool and

exciting hands on learning experiences that you are sure to enjoy and remember! A short

introduction to each project will help raise questions in your mind, followed by step-by-step

instructions for creating your project. Finally, our conclusion and learn more sections will help

you understand what your project demonstrates and how this information can answer

broader questions about science.

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Most of the items you will need for the experiments, such as jars, aluminium foil, scissors and

sticky tape, you can find around your home. Others, such as magnets, lenses or a compass,

you will be able to buy quite cheaply at a hobby shop or hardware store.

When you carry out experiments, always keep notes about the things you use (materials /

apparatus), what you do (method), and what happens (observations, results and conclusion).

All scientists do this. If an experiment does not work first time, dont be discouraged. Try

again. You may find there is something simple you have not done. Surprisingly, by doing

things wrong, you sometimes learn more than when you do things right!

TAPE NOTICE

In many of the science projects, an item known as sticky tape is required in the materials list.

With sticky tape, we only recommend any kind of adhesive tape which you would find most

suitable to the particular experiment.

Many types of adhesive tapes are available, from: masking tape which has a paper material

making it easier to tear, stick and write on; Sellotape which is stronger and is manufactured

from a plastic substance, Insulation tape is often used for insulating electrical wires and can

be used effectively where a waterproof bond is required. Duct tape, familiar worldwide is the

strongest and most versatile of all tape types.

Have fun experimenting!



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A WORD ABOUT SAFETY

RATHER BE A SAFE THAN SORRY SCIENTIST!

Science experiments should be enjoyable, interesting, and thought-provoking, but most

importantly, they should be safe to do! Some science experiments can however be dangerous.

Always ask an adult to help you with experiments that call for adult help, such as those that

involve matches or flames, hammers, or other dangerous materials. Don't forget to ask your

parents' permission to use household items, and put away your equipment and clean up your

work area when you have finished experimenting. Good scientists are careful and avoid

accidents.

Before you start, remember a few dos:

DO ask permission from your parents or another adult before trying any of the projects.

DO ask their advice if you do not understand what to do.

DO make sure you have all the equipment you need before you start.

DO carry out experiments with water over the sink or outside.

DO wear an apron to protect your clothes and wash your hands after every experiment.

and donts:

DONT touch anything hot with your bare hands

DONT use tins with jagged edges

DONT leave everything in a mess when you have finished



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ASK AN ADULT

ADULT SUPERVISION

While this book contains a collection of tried and tested science experiment and project ideas that

are safe and fun for children to do. It is nonetheless, every parent or teacher's responsibility to

supervise their children whilst performing our science experiments and to choose only the

experiments that they deem to be safe to do in and around their own homes or classrooms. Each of

our experiments clearly indicates whether it can be done by kids alone or if it should be done under

a parent's supervision.

Look for these warning symbols:

Although experiments marked with this symbol, are deemed safe to do by young

scientists on their own, it is always a good idea for adults to be involved whilst any

science experiments are carried out.

Experiments marked with this symbol, calls for the strict supervision of an adult to

stay with the young scientist throughout the duration of experiment. Experiments

marked with this symbol could contain dangerous items such as fire, chemicals or

sharp objects.

DISCLAIMER:

While Experiland.com makes every effort to provide science experiment & project ideas that are

safe and fun for kids, it is every parents own responsibility to supervise their kids whilst performing

these experiments and to choose only the experiments that they deem to be safe in their own

homes. Experiland.com will not take any responsibility with regard to injuries, losses, damages,

claims or any expenses arising out of or resulting from using our science experiments & project

ideas.



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HOW TO

HOW TO USE EXPERILANDS BOOKS Experilands science project e-books are divided into chapters based on the most general

subjects of science including: Chemistry, Earth science and Astronomy, Electricity and

magnetism, Life sciences and Physics with explanations of each subject at the start of each

chapter. Only The Mad scientist series of e-books are categorized by subject and therefore

contain only one subject per book.

In each chapter there are groups of projects that teach you about a specific scientific idea

within the general subject. Each experiment answers a particular question about science and

includes a list of the materials you need, easy-to-follow steps, and an explanation of what the

experiment demonstrates.

There is no need to buy special materials, but you may want to visit the library for additional

information on the topic. Most of the projects have a 'Learn more' section with relevant

information and fun science facts that are sure to surprise and amaze you. Explanations and

the conclusion are given at the end of each project. Some terms are displayed in inverted

commas and are defined in text and in the Glossary at the end of each project in the book.

Before you start any of the projects in this book, you should know a couple of things. Each

project has a difficulty level ranging from one to three. Simple projects are rated as one,

medium projects two and challenging projects get a three. Some projects also contain a red

caution sign. These projects involve things such as flames, hazardous chemicals, or sharp

objects. These projects should only be done with the help of an adult.

It might be possible that some projects may turn out differently than expected. Do not worry,

that happens to all scientists! If it does happen to you, try to figure out why it happened. Try

repeating the experiment, or change them in some way to see if that makes a difference. Be

accurate when conducting your experiments, follow the directions closely, and write down all

results. Be creative. See if you can come up with your own variations of some of the

experiments too. The best way for you, or any scientist, to learn is in a way that makes sense to

you.

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Be prepared

Some tips for completing the experiments:

Read through any experiment before you begin with the procedure.

Be organized Collect all the materials required before you start, and place them in the order in which

you will use them.

Keep clean Science can be messy, so wear old clothes while doing experiments and make sure to

give yourself enough space to work and enough ventilation. Cover surfaces with

newspaper in case of spills.

Be neat Keep your work and your work area as neat as you can. Use clean instruments, and

wash & put them away after every use.

HOW TO BE A GOOD SCIENTIST

Read through the instructions once completely and collect all the equipment you'll

need before you start any science experiment & follow the instructions carefully.

Develop the following habits:

If possible, keep a notebook. Write down what you do in your experiment or project

and what the results are.

Study your experiments carefully. Sometimes things happen very quickly and you may

have to redo an experiment more than once.

If your experiment or project does not work properly the first time, try again or try

doing it in a slightly different way. In real life, experiments don't always work out

perfectly the first time.

Always be open-minded and ask questions and look for answers. The basis of good

science is asking good questions and finding the best answers.

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Make small changes in the design of the equipment or project to see if the results stay

the same. Change only one thing at a time so you can tell which change caused a

particular result.

Never stop learning:

Make up your own experiment to test your own ideas about how things work.

Look at things in real life for examples of the scientific principles that you have learned.

Do not worry if you do not completely understand a particular project. There are

always new things to discover. Remember that many of the most famous discoveries

were made by accident.

Inquisitiveness

The 5 main qualities a good scientist should have?

The tendency to ask WHY, HOW, WHAT...

Determination Hard working with a never quit attitude!

Confidence Believing in oneself is the most powerful tool to succeed.

Creativity Ability to think 'out of the box'

Open-mindedness Listen to all sources of information and examine them thoroughly.



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METRIC & IMPERIAL UNIT EQUIVALENTS

The imperial system was first defined by the British in the 1800s, but by the late 20th century, most nations around the world officially adopted the metric system as their main system of measurement. Traditionally, the United States used to, and in many cases, continues to prefer the British Imperial system over metric measurements. The metric system is the basic system of measurement nowadays and is currently used in most countries around the world. As both metric and imperial units are still in general use, you might need to be able to convert between the two systems. The handy list below contains a number of useful conversion factors which might come in helpful in the science projects and science experiments contained in this book:

Metric Units

CAPACITY (LIQUID & DRY MEASURES)

Imperial Units 1 mL = 0.2 teaspoon = 0.07 tablespoon = 0.004

cup 1 Fluid ounce = 2 tablespoons = 30 millilitres = 0.03 litre

1 Teaspoon = 100 drops = 5 millilitres = Vi tablespoon 1 Pint = 2 cups = 480 millilitres = 0.47 litre 1 Tablespoon = 3 teaspoons = Vi fluid ounce = 15

millilitres 1 Quart = 4 cups = 32 fluid ounces = 960 millilitres

= 0.95 litre 1 Cup = 16 tablespoons = 8 fluid ounces = 240

millilitres = 0.24 litre 1 Gallon = 4 quarts = 128 fluid ounces = 3.8 litres

1 Litre = 1,000 millilitres = 61.02 cubic inches = 34 fluid ounces = 4.2 cups = 2.1 pints = 1.06 quart (liquid) = 0.908 quart (dry) = 0.26 gallon

Metric Units

VOLUME

Imperial Units 1 cm = 1,000 cubic millimetres = 0.06 cubic inch 1 Cubic inch = 16.38 cubic centimetres 1 m = 1,000,000 cubic centimetres = 35.3 cubic

foot = 1.3 cubic yards 1 Cubic foot = 0.028 cubic meter = 1728 cubic inches =

0.037 cubic yard 1 Cubic yard = 27 cubic feet = 0.76 cubic meter

Metric Units

WEIGHT Imperial Units

1 Gram = 0.035 ounce = 1,000 milligrams = 0.002 pound

1 Ounce = 28 grams = 437.5 grains = 0.06 pound

1 Kilogram = 2.2 pounds = 1,000 grams 1 Pound = 16 ounces = 454 grams = 0.45 kilogram = 7,000 grains

1 Metric ton = 1,000 kilograms = 1.1 tons 1 Ton = 2,000 pounds = 0.9 metric ton

Metric Units

LENGTH & DISTANCE Imperial Units

1 mm = 0.039 inch 1 Inch = 25 millimetres = 2.54 centimetres = 0.025 meter

1 cm = 10 millimetres = 0.39 inch = 0.03 foot 1 Foot = 12 inches = 30 centimetres = 0.3 meter 1 m = 100 centimetres = 1,000 millimetres =

39.37 inches = 3.28 feet = 1.09 yards or 1 yard + 3.4 inches

1 Yard = 3 feet = 36 inches = 90 centimetres = 0.9 meter

1 km = 1,000 meters = 0.6 mile 1 Rod = 5.5 yards = 16.5 feet = 5.03 meters 1 Mile = 1,609.3 meters = 1.6 kilometres

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Metric Units

AREA

Imperial Units 1 cm = 0.15 square inch 1 Square inch = 6.45 square centimetres 1 m = 10.76 square feet = 1.19 square yards 1 Square foot = 0.09 square meter 1 Hectare = 2.47 acres 1 Square yard = 0.83 square meter 1 km = 0.38 square mile 1 Square rod = 30.25 square yards = 0.0062 acre = 25

square meters 1 Acre = 43,560 square feet = 4,840 square yards

= 160 square rods = 0.4 hectare = 4,047 square meters

1 Square mile = 640 acres = 2.59 square kilometres

TEMPERATURE To convert Fahrenheit to Centigrade degrees, use the following formula: 5/9 (F - 32) = C To convert Centigrade to Fahrenheit degrees, use the following formula: 9/5 C + 32 = F Centigrade is also called Celsius

COMMON METRIC PREFIXES This table shows the most commonly used SI prefixes:

Prefix Symbol Factor Numerically Name giga G 109 1 000 000 000 billion* mega M 106 1 000 000 million kilo k 103 1 000 thousand centi c 10-2 0.01 hundredth milli m 10-3 0.001 thousandth micro 10-6 0.000 001 millionth nano n 10-9 0.000 000 001 billionth*

* The terms billion, trillion, etc., can be ambiguous. The terms are used here in the American English sense, but British English traditionally defined billion as a million million, rather than a thousand million. However, recent British usage tends to match the American meanings. ** Although unit names are ordinary words, note that unit symbols are case-sensitive, so uppercase and lowercase letters have different meanings. For example: mm is the millimetre (one-thousandth of a meter), but Mm is the mega meter (one million meters).



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CHEMISTRY What is Chemistry all about?

Chemistry is the study of matter in the form of atoms, molecules, and the interactions that

happen between them called chemical reactions. In its vast sense, chemistry is actually the

science of all the available materials that make up the world around you. This includes all

matter that you can see, hear, smell, taste, and touch! Matter is everything that has mass and

occupies space and all matter is composed out of the basic building blocks we call atoms.

Around 100 atoms are known to exist in the universe and are recorded and categorized in a

chart called the periodic table of elements. The names of just some of these elements will be

familiar to most people and includes elements such as oxygen; iron; helium; platinum and

chlorine. Knowing these elements can almost be seen as part of our general knowledge. These

basic building blocks or elements can react with one another to form a number of various

interesting combinations that are called molecules. Through the breaking and forming of atomic

bonds or molecules, various substances can change into new substances, either releasing or

consuming energy during the process or chemical reaction.

The marvel of chemistry is that when these basic particles are combined to form molecules, they

produce something new and unique. These new substances are either formed during natural

chemical reactions or are deliberately produced by chemists, to obtain specific desirable

qualities that were not present in the original materials! One of the main functions of a chemist

is to rearrange the atoms of known substances to produce new products useful to mankind.

Such new materials can be anything from stronger materials used in the manufacturing industry

to medicine or drugs which could help to cure and heal diseases.

Understanding the basic characteristics of all matter and learning how to predict and explain

how they change when they react to form new substances, is what chemistry and chemists are

all about!



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CHEMISTRY SCIENCE EXPERIMENTS

TABLE OF CONTENTS: [CHEMICAL ANALYSIS]

1. STRETCH YOUR IMAGINATION

Study how temperature affect the stretch of an elastic band....013

2. SPUD STARCH TEST Use iodine to test for the presence of starch in foods....015

3. FALLING LEAVES Use chromatography to predict the fall colour of a green leaf tree.017

4. TESTING ONE, TWO, THREE Use red cabbage as an indicator to test if a substance is an acid or base..019

5. HIGH PROTEIN FOOD FOR THOUGHT Test and compare the protein content in various everyday foods.....021

6. AND NOWTHE WEATHER FORECAST Use cobalt chloride as a humidity detector to predict the possibility of rain.023

[CHEMICAL REACTIONS]

7. HOW IS WATER MADE? Use electrolysis to find out what substances water is made of..025

8. UP IN A CLOUD OF SMOKE Make a slow burning smoke bomb...027

9. ELEPHANT TOOTHPASTE Produce a huge heap of foam in this exothermic reaction..029

[ELEMENTS & COMPOUNDS]

10. ONCE THE BALLOON HAS GONE UP

Demonstrate how molecule size affects its ability to escape from a balloon....031

11. DONT BURN YOUR FINGERS TO SNUFF A CANDLE Snuff out a candle by pouring carbon dioxide gas over it.033

12. THE C IN CITRUS CHEMISTRY Test how oxygen affects the amount of vitamin C contained in orange juice...035



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STRETCH YOUR IMAGINATION Study how temperature affect the stretch of an elastic band

CHEMISTRY > CHEMICAL ANALYSIS RN: 11030301

SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 12 Hours ADULT SUPERVISION ADVISED

STUFF YOU WILL NEED (MATERIALS):

Elastic band Washers Shoebox Scissors Ruler Hair dryer Nail

HOW TO PROCEED (METHOD): Polymers are compounds made of very long chains of molecules which often have plastic or rubber properties. An elastic band is made up of long polymer chains giving it its elastic properties. Apart from the fact that you can have a lot of fun shooting an elastic band across a classroom, they are quite fascinating in other ways too! In this science experiment study the effect temperature has on polymeric substances such as a rubber band:

1. Remove the lid from a medium sized shoebox and let it stand vertical. Use a nail to poke a small hole in

the centre of the top side of the box.

2. Cut a rubber band open and tie a few washers to one of its ends while the other end is pushed through

the hole in the top of the shoebox. Tie a knot around a nail on the top side so that the washers are

suspended inside the shoebox.

3. Stick a ruler on the back of the shoebox so that you can take measurements of the length of the band.

4. Now, let the rubber band stretch out for about 2 minutes at normal room temperature, then record its

length with the ruler at the back of the box.

5. Place the shoebox in the refrigerator for 20 minutes and again measure the length of the rubber band

and record your findings.

6. Next, use a hair dryer on its hot setting to heat the rubber band in the shoebox for about 3 minutes.

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Measure the length of the rubber band once again and record your observations.

7. You will notice that the rubber band contracts when heated and expands when cooled!

WHY IT WORKS (CONCLUSION): In this science experiment the rubber band, unlike most other substances, expands when cooled and contracts when heated! Rubber contains polymers (a large molecule that is usually described as a spaghetti-like strand) and these polymers give the rubber its elastic property. Rubber is a type of polymer called an elastomer. A property of a substance called entropy determines whether a material expands or contracts when heated. Entropy measures how ordered the molecules of a substance are arranged. When energy or heat is added to most substances, it excites the molecules causing them to move around vigorously, and hence the substance expands. However, when a polymer chain is heated, only sections of the chains move around vigorously and the other ends of the chain have to make room for the movement. This can be demonstrated by moving a piece of cooked spaghetti around on a plate The ends have to move closer together in order for the middle part to move further apart.

LEARN MORE: These days, most rubber is produced using petroleum. However, more than one quarter of all rubber produced is derived from latex, extracted from living trees. The two sources produce different types of rubber with different properties. Styrene butadiene, were one of the first forms of synthetic rubber ever produced and is still the major form of rubber produced today. Natural rubbers are made from elastic latex contained in some plants. Most natural rubber comes from a single species of tree, Hevea brasiliensis, which comes originally from South America, but is lately planted in large plantations in south-east Asia. Latex is extracted by removing thin strips of bark from the trees. The latex then flows down grooves cut in the tree and drips into collection cups.

GLOSSARY: Polymer A long or larger molecule consisting of a chain or network of many repeating units, formed by chemically bonding together many identical or similar small molecules called monomers. Elastomer Any polymer having the elastic properties of rubber. Entropy The amount of order or disorder present in a thermodynamic system. Entropy measures how ordered the molecules of a substance are arranged and hence determines whether a material expands or contracts when heated.



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SPUD STARCH TEST Use iodine to test for the presence of starch in foods


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 12 Hours ADULT SUPERVISION REQUIRED!


Cooking pot Bowl of water Large raw potato Piece of cloth 2x Coffee filters & funnel 2x Drinking

glasses Iodine solution

HOW TO PROCEED (METHOD): Starch is made up of long chains of glucose molecules. When starch is combined with hot water it breaks up into a kind of starch/sugar molecule called dextrin. When the dextrin is heated further, it breaks up into even finer sugar molecules called maltose. In this science experiment you will use iodine to test for the presence of starch in a potato:

1. Grate a large raw potato and place the gratings in the centre of a piece of cloth or netting. Roll the

gratings up into a ball by twisting the cloth several times around the grated potato. Place the ball of

grated potato inside the cloth in a bowl of warm water and squeeze out the starch for a few minutes

until the water becomes very cloudy. Remove the cloth and throw the potato gratings away.

2. Fill glass 1 half full with this raw starchy water. Slowly and carefully pour the rest of the starchy water

through a coffee filter into a kitchen sink, so that you are left with only the sticky potato starch in the

filter. You can place the coffee filter into a funnel to make this pouring easier.

3. Allow a few hours for the filter to completely dry out so that the starch becomes a thin white crust and

then break the starch up into small pieces.

4. Now, place about two teaspoons full of the small pieces of starch into a cooking pot and ask your

parents or an adult to heat it up on a stove until it turns brown. When brown, add 1 cup of water to the

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starch and stir the mixture.

5. Now, pour this heated brown starch / water mixture in glass 2 and allow it to cool off.

6. Add three drops of iodine to each of the glasses and swirl them gently. Notice how the water in glass 1

turns deep blue and the water in glass 2 turns deep red!

WHY IT WORKS (CONCLUSION): In this science experiment we use a chemical reaction that changes the colour of an indicator (iodine) when there is a certain concentration of starch in a given volume of water. When iodine comes in contact with starch, a deep purple-blue coloured substance is formed, and is a positive test for starch. A starch molecule is much larger than a sugar molecule and when starch is heated, it breaks apart into the smaller sugar molecules and allows it to be more easily digested. The liquid in glass 1 still contains raw starch pressed out of the potato, and therefore the iodine makes the solution turn deep blue. The liquid in glass 2 contains no more starch, as heating it up further caused the starch to be broken up into a fine sugar, hence the colour is turned deep red/orange indicating that no starch is present anymore.

LEARN MORE: Starch-rich Foods Must be Cooked Thoroughly if they are to have fine flavour and be easily digested. This is because starch occurs in foods in the form of tiny, hard, dry grains which are not soluble in cold water and which are difficult for the digestive juices to act upon. When starch is cooked, it is easy to digest and much improved in flavour, because cooking changes the form of the starch.

GLOSSARY: Starch Starch is a carbohydrate consisting of a large number of glucose units joined together. Food rich in natural starch is potatoes, rice and bread. Indicator Any substance used to classify another, often by changing colour. Iodine A non-metallic element belonging to the halogens. Iodine is used especially in medicine and photography and in dyes. It occurs naturally only in combination in small quantities as in sea water or rocks.



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FALLING LEAVES Use chromatography to predict the fall colour of a green leaf tree


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 2 Days ADULT SUPERVISION ADVISED


Green tree leaves Coffee filters Scissors 3x Small glass jars 3x Pencils Rubbing alcohol Ruler

HOW TO PROCEED (METHOD): In a process called chromatography, scientists can separate the individual parts of a mixture so that each one can be identified separately. In the following science experiment, use chromatography to analyse which other pigments are present in green leafs, to try and predict what colour the leaves will turn in the fall:

1. Collect one green leaf from at least three different types of trees. Good types of tree leaf to be used for

this experiment are: Birch, White oaks, Maple or Ash trees. Use a tree guide to help you identify the

trees and keep a sample of each type of leaf used for the experiment in the book.

2. Use scissors to cut coffee filters into three 25mm wide x 120mm long testing strips.

3. Wrap the ends of the three testing strips around the centre of three different pencils, and fix it in place

so that when the pencil rests on top of a small glass jar, the strip will hang into the glass without

touching the bottom or sides.

4. Place the first leaf type near one of the ends of the testing strip, approximately 25mm away from the

end, and use any hard object to rub back and forth over the leaf until you have a horizontal line of leaf

pigment on the strip.

5. Pour a little rubbing alcohol into a small glass jar. Suspend the testing strip from a pencil or similar so

that this pigmented end dips into the alcohol in the bottom of the glass jar, but make sure that the

pigment line itself is above the alcohol level.

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6. Wait about 30 minutes until the alcohol spreads slowly trough the testing strip and through the pigment

line. Like magic, different colours will start to appear above the pigment spot. These are the different

coloured pigments that are contained in various types of green leaves, but are hidden by the

chlorophyll in the leaves.

7. Repeat the whole procedure for the remaining two types of leaves and repeat the entire experiment

once the trees have changed to their fall colour. Compare your results to the green leaves and make a

data chart!

WHY IT WORKS (CONCLUSION): In this science experiment you can predict the colour that green leaves will turn in the fall by separating all the colour pigments contained in a green leaf, in a process called chromatography. During chromatography, the rubbing alcohol (solvent) moves up the paper by capillary action, this occurs as a result of the attraction of the alcohol molecules to the paper. As the alcohol rises through the paper, it meets and dissolves the pigment, which will then travel up the paper with the alcohol solute sample. Different compounds in the sample mixture (the pigment) travel at different rates due to competition between the paper fibres and water for the solutes. The pigments found in leaves are used in a plants food making process, called photosynthesis. Different colour pigments absorb different wavelengths of light to make this process more efficient for the plant. The main pigments are Chlorophyll A and Chlorophyll B, which causes the green colour of a leaf. Other pigments you may see are: yellow pigments (xanthophylls - Birch & Ash trees), orange pigments (carotenes Maple trees) or Brown / Red pigment (anthocyanins - White oaks).

LEARN MORE:

The first chromatograph was invented by Russian botanist Mikhail Tsvett (1872-1919) while he was looking for a method of separating a mixture of plant pigments (different types of chlorophyll) which are chemically very similar to each other. Hes technique, called absorption chromatography, could also be used to separate various colourless substances.

GLOSSARY: Pigment A substance whose presence in plant or animal tissues produces a characteristic colour. Chromatography An analytical chemistry technique for separating and identifying mixtures that are or can be coloured, especially pigments. Capillary action The flow of liquids through porous media, such as the flow of alcohol through a type of blotting paper like a coffee filter strip.



19

TESTING ONE, TWO, THREE Use red cabbage as an indicator to test if a substance is an acid or base


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 2 Days ADULT SUPERVISION REQUIRED!


Red cabbage Metal pan Strainer Timer Measuring cup Magic marker Plastic bowl

5ml Lemon juice 5ml Distilled water 5ml Baking soda 5ml Vinegar 5ml Ammonia 5x Small jars Adult helper

HOW TO PROCEED (METHOD): Chemistry can be used to test chemical substances to identify or learn more about them. Every chemical substance has different properties, for instance different melting points, different colours, and it may or may not combine with certain other chemical substances. Indicators are substances that are used to tell whether a chemical is an acid or base. Acids and bases are opposites and cancel each other out or neutralizes when mixed together. Litmus paper is an indicator and turns red when mixed with an acid or blue when mixed with a base. In the following science experiment we will learn more about this by using juice from red cabbage as a chemical indicator:

1. Ask your parents or an adult to boil some finely cut red cabbage leaves in a metal pan on a stove

together with about 6 cups of water. The water and red cabbage mixture needs to be boiled for about 5

minutes.

2. Using a strainer, strain the cabbage and water mixture over a bowl and then throw the leaves away.

Allow the remaining red cabbage coloured liquid to cool in the bowl.

3. Find 5 small glass containers, and using a magic marker, number each one from 1 to 5.

4. Now, pour about half a cup (125 ml) of the cooled red cabbage juice into each of the 5 glass containers.

5. Add one teaspoon (5 ml) of each of the following substances to the various glass containers: Lemon

juice to jar 1; Vinegar to jar 2; Distilled water to jar 3; Baking soda to jar 4 and Ammonia to jar 5.

6. Study the colour that each chemical turns the cabbage juice, and record your findings on a chart similar

to the one below:

Glass container Chemical substance Acid / Base Colour

1 Lemon juice Acid

2 Vinegar Slightly acid

3 Distilled water Neutral

4 Baking soda Slightly base

5 Ammonia Base

20

WHY IT WORKS (CONCLUSION): This science experiment works because when a chemical indicator is mixed with a chemical substance that is an acid or a base, a chemical reaction occurs. When the chemical reaction occurs, the acid or base changes the structure of the atoms or the indicator, by changing the way the electrons of the acid or base fit around the nucleus of its atoms, and thus causing the changing of the colour of the indicator. Cabbage juice is a chemical indicator in that it changes colour depending on the type of solution added to it. Compare your chart to the chart below indicating the expected results for this experiment:

Glass container Chemical substance Acid / Base Colour

1 Lemon juice Acid

2 Vinegar Slightly acid

3 Distilled water Neutral

4 Baking soda Slightly base

5 Ammonia Base

LEARN MORE:

You can make your own cabbage juice litmus paper by soaking blotting paper in a cup (250 ml) of the cabbage juice made in the above experiment. Let it soak for about 20 minutes and then place it on a piece of newspaper to dry for a few hours. After it has dried, cut it into several strips of about 10x50mm for easy use. You can use an eyedropper to place a drop of each of the substances in the experiment above ,on a piece of paper to see if the result is the same. Use the remaining strips of your litmus paper to test other chemicals in the kitchen, such as: milk, Soy juice, cold drink and many more. Have fun!

GLOSSARY: Chemical reaction The formation of new substances from one or more reactants, by breaking existing electrical bonds and creating others. Litmus A colouring material (obtained from lichens, a composite organism consisting of fungi) that turns red in acid solutions and blue in alkaline solutions. It is used as a very rough acid-base indicator. Acid Any water-soluble compound having a sour taste and capable of turning litmus red and reacting with a base to form a salt. Acid has a pH-level of less than 7.0 (A pH of 7 is neutral). Base The opposite of an acid. A Base has a pH-level of more than 7.0 up to 14.0 (A pH of 7 is neutral)



21

HIGH PROTEIN FOOD FOR THOUGHT Test and compare the protein content in various everyday foods


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED



Metal pan Bowl Glass jar with lid Copper-sulphate solution Lye (Sodium hydroxide) 5x Plastic cups Spoons

Milk Egg white Banana Kidney Beans Mince meat Magic marker Medicine dropper

HOW TO PROCEED (METHOD): Proteins have many different jobs within our bodies. The body mainly uses proteins for energy. Protein is also used as an enzyme, which starts reactions within the body such as metabolism, gene growth and repair. Meat and dairy products are foods which are rich in protein. In this science experiment, test for proteins in some everyday foods to see which have the highest content:

1. Use five separate disposable plastic cups to place the following food samples inside: milk, egg white,

banana, kidney beans and mince meat. Fill the cups with the food samples only about 1/3rd full. The

banana, kidney beans and mince meat should first be mixed with water and each sample boiled

separately in a metal pan until it forms a thin paste that can be used as the sample.

2. When all the food samples have been prepared and placed inside the cups, use a magic marker to label

the cups according to the food it contains.

3. Now, ask your parents or an adult to help you prepare lye solution. Lye solution is very alkaline and

should be handled with extreme care. Lye powder can be obtained from your local hardware store.

Pour about cup of warm water into a glass jar and use a plastic teaspoon to add lye powder to the

water, until no more powder will dissolve in the water. Place the lid on the jar and label the jar: Lye

solution - Caution with the magic marker.

4. Next, use the medicine dropper to transfer the lye solution to each of the food samples in the cups,

making sure that each cup contains about 1/3rd food and another 1/3rd lye solution. Each cup should

contain as much lye solution as food. Rinse the medicine dropper.

5. Use a plastic teaspoon to mix each of the food / lye mixtures in each cup. Rinse the spoon each time

after mixing a sample.

6. Once again, use the medicine dropper to add 4 drops of copper-sulphate solution to each of the samples

in the cups, and notice the changes in colour of each mixture. Some of the samples will turn brilliant

violet in colour, whilst other may show little or no change at all!

22

WHY IT WORKS (CONCLUSION): In this science experiment, the food samples which have the highest content of protein turns a brilliant violet colour when the copper-sulphate solution drops are added. We use a chemical reaction that changes the colour of an indicator (copper-sulphate solution) when there is a certain amount of protein contained in a given volume of a food sample. The fewer protein contained by a certain food, the less colour change is present when the copper-sulphate solution drops are added. The solid foods used in this experiment needed to be mixed with water and boiled into a paste to break down the protein, to enable you to test for it easier.

LEARN MORE: Proteins are compounds made by combining amino acids. Proteins in the diet are known as macro-nutrients, and contribute energy or calories to the body. Each gram of protein contains 4 calories. There are 20 amino acids used to build proteins. Proteins that do not have all 20 amino acids are called incomplete proteins. Protein sources containing all 20 amino acids are referred to as complete proteins. Eating complete protein sources will ensure you are getting all of the amino acids that your body needs. Complete proteins include meat, poultry, fish, dairy, eggs, and soy (a non-animal source). Nuts, grains, fruits, and vegetables are typically incomplete. Protein deficiency is a state of malnutrition in which inadequate amounts of protein is taken in for the body to use in order to produce energy. This condition is largely to blame for the high rate of starvation in many Third World countries, as well as in developed countries, primarily due to poverty. When a body is in a state of protein deficiency, it signals its system to enter into starvation mode in which the body attempts to balance for the deficiency by pulling out supplies of protein in the body for recycling. The first source the body will turn to make a protein withdrawal is the muscles, which leads to a condition known as muscle wasting and is one of the first symptoms of protein deficiency.

GLOSSARY: Protein Any of the amino acids present in all living matter that are an essential food item. Enzyme Complex proteins produced by cells that facilitates or speeds up certain bio-chemical reactions in the body. Lye Lye is a strong alkaline substance, commonly sodium hydroxide or 'caustic soda' (NaOH). Indicator Any substance used to classify another, often by changing colour.



23

AND NOWTHE WEATHER FORECAST Use cobalt chloride as a humidity detector to predict the possibility of rain


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 2 Weeks ADULT SUPERVISION REQUIRED!


Cobalt chloride White blotting paper White writing paper White cloth Clothespins Teaspoon Measuring jug

HOW TO PROCEED (METHOD): The humidity in the air can be explained as the amount of water a volume of air holds, and is expressed as a percentage. The humidity level is often seen as an indication of the likelihood of rain occurring, and this is usually measured with a hygrometer. A chemical humidity detector or hygrometer can be made by dipping a piece of paper or cloth in a solution of cobalt chloride, as you will see in the following science experiment: Warning: Exercise extreme caution when working with Cobalt chloride. Do not touch or inhale the solution as it can be hazardous to your health! Ask your parents or an adult to help you with this experiment.

1. Obtain some cobalt chloride solution from your local chemist. Some chemistry sets might also contain

this solution.

2. Dissolve about teaspoon of the crystals in about 100ml of water in a large measuring jug.

3. Take turns to thoroughly soak each of the pieces of paper and the piece of cloth in this solution.

4. Remove the materials from the solution after soaking for about 1 minute each, and place the items

somewhere outside to dry. Make sure that it is out of reach of pets or other humans.

5. When dry, it will turn blue and your testing materials are ready to use.

6. The material will turn pink when there is a considerable amount of humidity in the air, indicating that

there might be a possibility of rain occurring. Some materials might work better than others, thus

24

experiment with the blotting paper, writing paper and cloth, to see which works the best as an indicator.

7. Experiment with your indicator material by placing it at several places around the house inside and out,

by hanging it from objects with a clothespin or sticking it to the wall with sticky tape.

8. Keep a chart for a few weeks to check how closely your indicator checks with the actual weather

conditions. Record the date and hour, indicator colour, weather condition and relative humidity

measured with a real hygrometer and compare your results!

WHY IT WORKS (CONCLUSION): This science experiment works because when cobalt chloride comes in contact with water molecules, it forms a hydrate. The formation of the hydrate, wherein one or more water molecules are incorporated into the anhydrous salt, forms a new crystal structure that causes the colour change from blue to pink. This happens because the water molecules become incorporated into the newly formed crystals.

LEARN MORE: Chemical compounds of the element cobalt have been used for thousands of years as colouring agents in paint, ink, ceramics and glass. Cobalt glass, for example, owes its attractive deep blue colour to a compound of cobalt and oxygen, cobalt oxide, Cobalt chloride has also long been used to predict the presence of water molecules within the air. It is also included in some indicating silica gels and kitty litters to show when they have reached their absorption capacity. Cobalt chloride is labelled as carcinogenic if inhaled, but as of yet is not banned for use in the US. There are various non-carcinogenic alternatives to indicate moisture absorption available.

GLOSSARY: Hygrometer Measuring instrument for measuring the relative humidity of the atmosphere. Humidity The relative humidity is a measure of the amount of water vapour in the air (at a specific temperature) compared to the maximum amount of water vapour air could hold at that temperature, and is given as a percentage value. Cobalt chloride A chemical substance often used to predict the presence of water molecules within the air or other substance. Carcinogenic A carcinogenic substance is any substance that produces cancer or stimulates the production of cancerous cells.



25

HOW IS WATER MADE? Use electrolysis to find out what substances is water made of

CHEMISTRY > CHEMICAL REACTIONS RN: 10083102

SUITABLE GRADES

DIFFICULTY

TIME REQUIRED



Bowl of water Carbon rods Long match 9 volt battery 2x Test tubes

HOW TO PROCEED (METHOD): All chemical substances or elements can be described in a shorthand method, for example H O for water, or CO for carbon dioxide. Chemists often use this method of describing all the chemical substances, better known as a substances chemical formula. A chart known as the periodic table contains all the chemical elements according to their atomic number, weight, density and more. For instance Hydrogens formula is H and oxygens formula is O and waters chemical formula is known as H O. This shows us that water is made up of 1 part oxygen and two parts hydrogen. Prove this is true in the following exciting science experiment the electrolysis of water:

1. Use a 9-volt battery for this experiment. Please do not use any other means of electricity as this could

be very dangerous!

2. Obtain two small carbon rods (the electrodes) from your hardware store and connect a wire to each of

them. Then, connect the other ends of the wires to the positive and negative terminals of the battery.

3. Place the electrodes in glass test tubes filled with water as in the diagram above and place these in the

bowl of water. The two carbon electrodes will carry the electric current into and out of the water in the

bowl.

4. Once the battery is connected and all items have been set up as per the instructions, you will notice that

bubbles of gas will start to rise from the carbon rods or electrodes.

5. The gas will collect in the top of the tubes and after a while you will notice that the one tube contains

twice as much gas as the other (The hydrogen).

26

6. Ask your parents or an adult to help you test these gasses in the following matter: Take the first test

tube out of the water and immediately drop a lighted match into it you will hear a loud pop as the gas

inside burns up rapidly indicating it is hydrogen. Do the same with the second test tube but drop a

glowing, not a burning match inside. It will burst into flames indicating it is oxygen gas.

WHY IT WORKS (CONCLUSION): In electrolysis, the anode is the positive electrode and is where oxidation takes place. Oxidation involves the loss of electrons. The cathode is the negative electrode and is where reduction takes place. Reduction involves gain of electrons. Think of water as hydrogen oxide (H2O). We can consider each hydrogen portion of water as H+. These would have to gain electrons (-) to become neutral hydrogen, therefore, this must happen at the negative electrode (the cathode). We can consider the oxygen part of water as O2- which has a negative charge hence would have to lose electrons to become neutral. Thus, oxygen gas should form at the positive electrode (the anode).

The presence of ions in the solution is what allows water to conduct electricity. Pure water is actually not a conductor. It has an

LEARN MORE:

electrical conductivity of about one millionth of that of seawater. However, unless the pure water has been properly de-gassed and de-ionized it will contain enough dissolved ions to make it conductive. When a salt is dissolved in water it yields ions. The efficacy of electrolysis is increased through the addition of an electrolyte (such as a salt, an acid or a base)

GLOSSARY: Chemical element Any of the more than 100 known substances that cannot be separated into simpler substances and that individually or in combination constitute all matter. Periodic table A tabular arrangement of the chemical elements according to atomic number as based on the periodic law. Oxygen Oxygen, scientifically known as O2, occupies about 21 percent of the earths atmosphere and is also found in other substances including water. It can combine with many other elements and it is essential for plants & animals to breathe. Oxygen is also required for nearly all combustion. Electrolysis The process by which we generate hydrogen and oxygen from water is called electrolysis.



27

UP IN A CLOUD OF SMOKE Make a slow burning smoke bomb


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED



Sugar Potassium nitrate Spoon String & lighter fluid

Metal pan Aluminium foil Adult helper

HOW TO PROCEED (METHOD): A smoke bomb is a type of firework designed to produce smoke upon ignition. Smoke bombs are often used in the military, recreational games, self defence and you can even use it for pranks on your friends! Commercial smoke bombs is usually made from potassium chlorate, sugar used as fuel, sodium bicarbonate (baking soda - to moderate the rate of the reaction and keep it from getting too hot), and a powdered organic dye. Crafting such a type of smoke bomb can be quite complex, but you can make an effective and safe smoke bomb quite easily in this science experiment:

1. Ask your parents or an adult to help you with this experiment. Place a pan on slow heat on the stove.

2. Pour about 3 parts (1, 5 cups) potassium nitrate to 2 parts (1 cup) sugar into the pan. Potassium nitrate

(KNO3) also known as saltpetre, can be purchased at garden supply stores and some pharmacies.

3. Stir the mixture with a spoon using long strokes. The sugar will start to melt and form carbon. Continue

heating/stirring until all the ingredients are liquefied. When the substance turns to a caramel brown

colour, remove the pan from the heat. This is a similar process to making caramel candy.

4. Now, slowly pour the liquid onto a moulded piece of aluminium foil. You can pour the smoke bomb

liquid into any shape, onto an object. The shape and size will affect the burning pattern and you might

need to play with the shape and size to get the most effective shape.

5. Place a short length of fuse (about 50mm) into the smoke bomb liquid when you pour it into the

aluminium foil mould. To make the fuse, take a piece of string and soak it in a bowl of lighter fluid. Make

sure it is completely saturated then leave it in the sun to dry.

6. Allow the smoke bomb liquid to cool and dry, and then peel it off the aluminium foil.

7. Light the fuse of your smoke bomb, using a long-handled lighter, usually used for barbeque grills. Stand

back and watch the bomb burn up in a cloud of smoke!

IMPORTANT NOTICE:

Clean off the stove when you are done, to prevent it from making a reaction. Only light your smoke bomb in a well-ventilated area, on a surface that won't catch fire. The smoke bomb will burn with a purple flame. Do not burn the smoke bomb in a public area. Do not inhale the smoke.

28

WHY IT WORKS (CONCLUSION): In this science experiment, the sugar placed on a mild heat source is slowly oxidized into carbon dioxide and water. The nitrogen in the potassium nitrate will be reduced to nitrogen gas, and the potassium will end up as potassium carbonate (the carbon coming from the CO2 from the sugar). Smoke bombs use a formula that consists of an oxidizer (typically potassium chlorate, KClO3), a fuel (generally sugar in the form of dextrin), a moderant (such as sodium bicarbonate) to keep the reaction from getting too hot, and a powdered organic dye to add colour to the smoke. The burning of this mixture evaporates the dye and forces it out of the device, where it condenses in the atmosphere to form a smoke of finely dispersed particles. A ratio of 3:2 is suggested in this experiment, but the measurements do not need to be exact. Make sure that you use more KNO3 than sugar, or your smoke bomb will be harder to light and will burn more slowly. You get a smoke bomb that burns more quickly by using more KNO3 than sugar.

LEARN MORE: The modern smoke bomb was first created in 1848, by the inventor Robert Yale. He developed the Chinese fireworks from the 17th century and modified the formula to produce more smoke than before for a longer period of time.

GLOSSARY: Potassium nitrate (Saltpetre) KNO3 is a naturally occurring mineral source of nitrogen. Its common names include saltpetre or nitrate of potash. It is used in the production of nitric acid, model rocket propellants, and several types of fireworks. Dextrin A type of sugar composed of many glucose units. It is a tasteless, odourless gummy substance that is often used as a thickening agent, in adhesives and in dietary supplements. Smoke bomb Smoke balls are hollow, cherry-sized spheres of brightly-coloured clay filled with a smoke composition. They produce a forceful jet of coloured smoke usually for about 10-30 seconds.



29

ELEPHANT TOOTHPASTE Produce a huge heap of foam in this exothermic reaction


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED



Hydrogen peroxide solution (30%)

Liquid dishwashing detergent

Food colouring Potassium iodide (KI) solution

500ml cylinder or glass bottle

Match Safety glasses & gloves

HOW TO PROCEED (METHOD): The fight against elephant tooth decay is on! In this science experiment, you will produce a huge amount of steaming foam that sort of looks like the toothpaste an elephant might use:

1. Put on the safety glasses and gloves before you start with the experiment. To prevent iodine staining,

cover your work surface with a plastic sheet or some newspapers.

2. Pour about 50 ml of 30% hydrogen peroxide solution into a 500ml volume graduated cylinder.

3. Squirt a little dishwashing detergent in the cylinder and swirl it around.

4. Place a few drops of food colouring along the cylinder walls to make the foam resemble striped

toothpaste.

5. Add 10 ml of saturated potassium iodide solution. Stay clear of the mouth of the cylinder when you do

this. This is a forceful exothermic reaction and you may get splashed or burned by steam.

6. Stand back and watch the foam or toothpaste burst out from the mouth of the cylinder! To test for the

presence of oxygen, touch a glowing match or splint to the foam to re-light it.

IMPORTANT SAFETY NOTICE:

Protect your eyes and hands by wearing disposable gloves and safety glasses Oxygen is produced during this reaction, so do not perform this demonstration near an open flame. This is an exothermic reaction which produces a fair amount of heat. Do not lean over the graduated

cylinder when the solutions are mixed. The foam produced is just water, soap, and oxygen, so you can clean it up with a regular sponge.

WHY IT WORKS (CONCLUSION): The special foam or toothpaste you made in this science experiment contains foam bubbles, each filled with oxygen. The Potassium iodide is used as a catalyst to remove the oxygen from the hydrogen peroxide and the dishwashing detergent is responsible for capturing the oxygen in bubbles. This reaction happens very fast and lots and lots of bubbles are created in the process, producing a huge heap of foam. This experiment is an example of an exothermic Reaction, meaning that heat is created during the process. This experiment is sometimes called Elephant's Toothpaste because it looks like toothpaste coming out of a tube, but do not place the foam in your mouth or brush your teeth with it!

30

LEARN MORE: ENDOTHERMIC AND EXOTHERMIC REACTIONS COMPARED Endothermic reaction: Melting ice. In order for ice to melt, it needs to draw in the heat or energy from its surroundings. The ice becomes less stable as it responds to the increased heat. The ice's stored energy decreases. The end product is water, which has a higher energy level than the ice. Exothermic reaction: Lighting a match. When the head of the match is struck, it results in the spontaneous release of stored energy (heat) from the reactants into the surroundings. The flame that is produced has a lower level of energy than the match and the striking surface, because the reaction is giving off stored energy and not required to draw energy in from its surroundings.

GLOSSARY: Exothermic reaction A chemical reaction in which heat is given off during the formation of new chemical compounds. Catalyst A substance that initiates or accelerates a chemical reaction without itself being affected. Potassium iodide A white crystalline salt used in making photographic emulsions and in iodized table salt. Potassium iodide is an inorganic compound with formula KI. Hydrogen peroxide An almost colourless, slightly pale blue liquid. H2O2 is soluble in water. Hydrogen peroxide is used as a mild antiseptic and is often found in bleaching agents, especially for bleaching hair.



31

ONCE THE BALLOON HAS GONE UP Demonstrate how molecule size affects its ability to escape from a balloon

CHEMISTRY > ELEMENTS & COMPOUNDS RN: 11030302

SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 2 Weeks ADULT SUPERVISION ADVISED


4x Regular latex balloons

Large bucket Tap water Yardstick Friend Helium gas source

HOW TO PROCEED (METHOD): Balloons are a very popular gift amongst people all over the world. Many people give balloons to congratulate someone, say happy birthday or get well soon, but unfortunately, they do not last forever and all balloons deflate over time. Helium balloons are even more fun, but they always seem to deflate even faster than regular balloons! Polymers are compounds made of very long chains of molecules which often have plastic or rubber properties. A regular latex balloon is made up of long polymer chains, giving it its elastic properties, but this also make the substance a bit porous. In this science experiment, you will test how the size of a molecule affect its ability to escape from a balloon:

1. Blow up two balloons with air and blow up two balloons with helium (at a local fun park or other source

of helium gas). The balloons should all be inflated to roughly the same size.

2. You can measure the volume of each balloon by filling a large bucket or drum with water, submerging

each balloon in the water and asking a friend to measuring the water surface change with a yardstick.

Record the volume of each balloon.

3. To calculate the volume of the balloon, first calculate the area of the bucket, by multiplying its width

with its length if it has a square shape; or multiply is diameter with a factor 3.14 if it has a circular shape.

4. Once you have calculated the area of the bucket, multiply this number with the water surface

32

displacement (height difference of water level), using the same unit for example mm. Your calculation

will look something like the following: AREA (400mm Dia. x 3.14 = 1265mm) X DISPLACEMENT (25mm) =

5. Calculate the volume of all four balloons and record your data.

31625mm or 31.6 cm VOLUME OF BALLOON

6. Repeat all the steps once every 6-8 hours to see how the volume of each balloon decreases as the gas/air

inside gradually escapes, until the volume no longer changes or the balloon is completely deflated.

7. Make a data chart and graph indicating the rate of volume decrease by each balloon, and compare the

balloons filled with air with the balloons filled with helium gas!

WHY IT WORKS (CONCLUSION): Latex balloons are made out of natural rubber extracted from trees. The walls of a latex balloon have microscopically small pores or holes in them. Even though these holes cannot be seen by the human eye, they do exist and they are a lot larger than Helium atoms, hence the Helium atoms can easily escape from the inside of the balloon. Balloons filled with air hold their volume for a much longer period, because air particles, consisting mostly of Nitrogen (N2) and Oxygen (O2), are larger than Helium (He) particles, therefore causing them to escape more slowly than the Helium particles. This process whereby the particles escape through the latex, is referred to as diffusion. The material the balloon is made from, such as the latex or foil, affects how long the balloon will stay inflated. The more porous the material, the quicker the Helium or air particles will escape from it.

LEARN MORE: These days, most rubber is produced using petroleum. However, more than one quarter of all rubber produced is derived from latex extracted from living trees. Natural rubbers are made from elastic latex contained in some plants. Most natural rubber comes from a single species of tree, Hevea brasiliensis, which comes originally from South America, but is lately planted in large plantations in south-east Asia. Latex is extracted by removing thin strips of bark from the trees. The latex then flows down grooves cut in the tree and drips into collection cups.

GLOSSARY: Polymer A long or larger molecule consisting of a chain or network of many repeating units, formed by chemically bonding together many identical or similar small molecules called monomers. Porous Full of tiny pores that allow fluids or gasses to pass through. Diffusion The process by which a substance moves from an area of high concentration, through a barrier or membrane, to an area of lower concentration.



33

DONT BURN YOUR FINGERS TO SNUFF A CANDLE Snuff out a candle by pouring carbon dioxide gas over it


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED



Glass bottle Card Vinegar Baking soda Glass jar Candle

HOW TO PROCEED (METHOD): As you know, water is most often used to put out a small fire, or you can also make use of a wet cloth to smother the fire. Carbon dioxide also scientifically known as CO2, which is widely used in fire extinguishers are commonly used to put out fires because it is heavier than air. In this science experiment we will be putting out a fire invisibly by pouring carbon dioxide gas over a flame of a candle.

1. To represent the fire, light up a candle and place it in a glass jar on a table.

2. To make some carbon dioxide gas, mix together two tablespoons of baking soda with some vinegar in

a large pouring bottle. (The vinegar will make the soda fizz and in the process carbon dioxide gas is

released.)

3. Roll up the cardboard paper to form a tube. Then use it to carefully pour the carbon dioxide gas from

the bottle into the glass jar with the burning candle.

4. The candle will be snuffed out within a few moments as the heavier carbon dioxide gas pushes the air

(oxygen) out of the glass jar and put out the flame.

WHY IT WORKS (CONCLUSION):

When the carbon dioxide gas is poured from the container over the candle and is contained in the glass jar, the air (oxygen) is pushed upwards as the heavier-than-air carbon dioxide fills up the bottom of the jar. When the candles flame is below the air level, it is deprived of oxygen and is snuffed out. Nothing can burn without the

34

oxygen in air.

LEARN MORE: Fire happens when you have atoms such as carbon and hydrogen in the candle wick linking up with oxygen atoms in the air to form molecules, such as carbon dioxide. Every time a new molecule is formed, energy is released. This is the energy that we see as light and feel as heat in a candle flame.

GLOSSARY: Carbon dioxide Carbon dioxide is a colourless, odourless incombustible gas present in the atmosphere. It is formed during the breathing of living organisms, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates: used in fizzy drinks, fire extinguishers, and as dry ice for refrigeration. Fire extinguisher Any of various portable steel container devices for spraying and extinguishing a fire with Carbon dioxide or other chemicals. Oxygen Oxygen, scientifically known as O2, occupies about 21 percent of the earths atmosphere and is also found in other substances including water. It can combine with many other elements and it is essential for plants & animals to breathe. Oxygen is also required for nearly all combustion. NOTES: _____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________ _____________________________________________________________________________________________



35

THE C IN CITRUS CHEMISTRY Test how oxygen affects the amount of vitamin C contained in orange juice


SUITABLE GRADES

DIFFICULTY

TIME REQUIRED

< 2 Weeks ADULT SUPERVISION REQUIRED!


Orange juice Medicine dropper Tap water Bowl Cornstarch Iodine solution 6x Plastic cups

HOW TO PROCEED (METHOD): Vitamin C, also known as ascorbic acid, is one of the essential vitamins for good health. The actual function of Vitamin C is to maintain strong connective tissue. If a person has an inadequate amount over a long period of time, they will suffer the deficiency disease called scurvy. We all know how important it is to get enough Vitamin C in ones diet, but how long does Vitamin C in fruit juice last? Find out in the following science experiment:

1. Use a mixing bowl to mix together one cup of water and about 2 table spoons of cornstarch. Use a

spoon to mix the cornstarch well so that it completely dissolves in the water.

2. Add iodine solution to the mixture in the bowl, one drop at a time, until the mixture in the bowl turns a

dark purple-blue colour. This will be your indicator solution.

3. Place two table spoons (about 30ml) of the cornstarch / iodine mixture into a plastic cup.

4. To test the amount of Vitamin C contained in fresh orange juice, use a medicine dropper to soak up some

fresh orange juice, and then one drop at a time, add the juice to the cornstarch / iodine mixture in the

plastic cup. Gently swirl the liquid in the glass after every few drops, while counting and recording how

many drops of juice it takes to clear the purple-blue colour. This measures the concentration of vitamin

C in the juice. Record the number of drops on a data table.

5. Now, label 6 plastic cups with a magic marker, half of them covered and the other half uncovered and

add exactly the same amount of orange juice into each of them. Cover only the covered labelled cups

with plastic wrap and place them all in the refrigerator.

6. Using the same testing procedure as before (steps 3 & 4), test each of the orange juice samples after 24

hours in the fridge. Record the number of drops you used for each sample of juice in your data table.

7. Re-cover the covered cups and place them back into the refrigerator for testing again after another 24

hours.

8. Repeat this procedure once every 24 hours for all the orange juice samples, until no more vitamin C is

contained in it. The iodine / starch mixture will stay blue, no matter how much orange juice drops are

added. Make sure you record your data after each testing session and draw up a chart & line graph

comparing how long it took to eliminate the vitamin C from each sample type.

WHY IT WORKS (CONCLUSION):

36

In this science experiment we use a chemical reaction that changes the colour of an indicator (iodine) when there is a certain concentration of Vitamin C in a given volume of juice. When iodine is mixed with cornstarch and water, a deep purple-blue coloured substance is formed. When the juice drops are added and when enough Vitamin C is added to this indicator, the purple-blue colour

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