biology 6th -1.pdf

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Biology6th Form

Booklet 1


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Unit 1: Materials

RevisionSection 1: The Mixture of materials

Materials with different characteristics can be mixed.

Mixtures of different materials have different results.

Work with your teacher

Assignment # 1: MIXTURES

-Aim: To Observe the differences among a variety of mixtures.

- Materials:

7 Glass jars

Sand

Water

Oil

Chalk dust

Wine vinegar

Salt or sugar

Iron filings

- MethodsLabel the jars:

Glass jar 1: add water and a table spoon of sand. Stir the mixture

Glass jar 2: add water and a table spoon of salt or sugar. Stir the mixture

Glass jar 3: add water and a table spoon of chalk dust. Stir the mixtureGlass jar 4: add water and wine vinegar. Stir the mixture

Glass jar 5: add water and oil. Stir the mixture

Glass jar 6: add oil and a table spoon of salt or sugar oil. Stir the mixture

Glass jar 7: add sand and iron filing. Stir the mixture


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- ResultsWhat does each mixture look like? Draw and label the results of your

observations

Jar 1

Jar 2

Jar 3

Jar 4


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Jar 5

Jar 6

Jar 7

Discussion:

What happened in each jar? Does the mixture look homogenous or

heterogenous? How many phases can you count?

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Conclusion :

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Looking at the results of the assignment, what differences could you find

between jar 2 and jar 6?

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Section 2:Separating mixtures

The different substances in mixtures are usually easily separated from one

another. The method you use depends upon the type of mixture you have.

Chromatography

This is good for separating dissolved substances that have differentcolours, such as inks and plant dyes. It works because some of the colouredsubstances dissolve in the liquid better than others, so they travel further

up the paper.


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Filtration

Filtration is good for separating aninsoluble solidfrom a liquid. (An

insoluble substance is one that does not dissolve).

Sand, for example, can be separated from a mixture of sand and waterusing filtration. That's because sand does not dissolve in water.

Evaporation

This is good for separating asoluble solidfrom a liquid (a soluble substance

does dissolve, to form a solution).

For example copper sulphate crystals can be separated from copper

sulphate solution using evaporation. Remember that it is the water that

evaporates away, not the solution.

Simple distillation

This is good for separating aliquidfrom a solution. For example, water can

be separated from salty water by simple distillation. This method worksbecause the water evaporates from the solution, but is then cooled and

condensed into a separate container. The salt does not evaporate and so it

stays behind.


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Fractional distillation

This is good for separatingtwo or more liquidsfrom each other. For

example, ethanol (alcohol) can be separated from a mixture of ethanol andwater by fractional distillation. This method works because the two liquids

have different boiling points.

Magnetism

Magnetism is a form of separating mixtures which involves using a magnetto attract another magnetic object away from the substance it is in. Some

examples of separating magnetic substances from non magnetic substances

are: separating iron nails from glass chippings and separating iron paperclips from brass ones.


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ASSIGNMENT #2 : SEPARATING MATERIALS

Aims: To separate the different materials of a mixture.

Materials:

Glass jars 1, 2 and 7 from practical work # 1

Colour markers

A Magnet

A small plastic dish

2 clean glass jars

Alcohol

Coffee filterKitchen funnel

Cotton thread

Blotting paper

Methods

Part 1: Pour a small amount of the content of jar 2 over the small plastic

dish. Leave it until next class

Part 2: Filter the content of the glass jar 1 using the funnel, the filter

paper and a clean glass jar.

Part 3: Tie the magnet with the cotton thread. Introduce the magnet in

the glass jar 7. Shake gently the jar. Take the magnet out.

Part 4: Cut a square of 70 cm x 4 cm of blotting paper. Draw 3 dots of

different colours on one side of the square.

Pour a small amount of alcohol inside a clean glass jar. Place the paperinside the jar and close it.


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Results:

Draw your observations


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Discussion:

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Conclusions:

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Section 2:Water

WATER FACTS

Water is made up of two elements, hydrogen and oxygen. Itschemical formula is H2O.

The existence of water is essential for life on Earth. Water has three different states, liquid, solid and gas. The word waterusually refers to water in its liquid state. The solid

state of water is known as icewhile the gas state of water is known

as steamor water vapor.

Water covers around 70% of the Earths surface. The three largest oceans on Earth are the Pacific Ocean (the

largest), the Atlantic Ocean (the second largest) and the Indian

Ocean (the third largest).

Found in the Pacific Ocean, the Mariana Trench is the deepest knownpoint in the worlds oceans.

The longest river in the world is the River Nile which is 6650kilometers long (4132 miles).

The second longest river in the world is the Amazon which is 6400kilometres (4000 miles) long.

Water makes a good solvent with many sugars, salts and acids easilydissolving in it. On the other hand oils and fats dont mix well with

water.

The water cycle involves water evaporating (turning into a gas), risingto the sky, cooling and condensing into tiny drops of water or ice

crystals that we see as clouds, falling back to Earth as rain, snow or

hail before evaporating again and continuing the cycle. Learn more

about the water cycle.


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Water in the form of ice is found in the polar ice caps of Mars. Somescientists have also suggested the possibility of liquid water on the

red planet.

Pure water has no smell and no taste.

Most people around the world have access to clean drinking waterbut it is a major problem in poorer areas of the world. Water

pollution and low quality water can lead to dangerous bacteria,

disease and viruses such as E coli and Cryptosporidium.

Drinking water is needed for humans to avoid dehydration, theamount you need each day depends on the temperature, how much

activity you are involved in and other factors.

Water plays an important role in agricultural irrigation. This meansthat water is artificially added to soil in order to make the growth of

crops possible.

Water is used frequently by firefighters to extinguish fires.Helicopters sometimes drop large amounts of water on wildfires and

bushfires to stop fires spreading and to limit the damage they can

cause.

The water works helps deliver water to homes in various cities andcountries around the world. This can involve processes such as

purification, sewage treatment, filtering, distillation and plumbing.

Electricity can be created from hydropower, a process that useswater to run turbines connected to generators. There are many

hydroelectric power stations around the world.


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Water also plays a role in cooking. Steaming and boiling food are wellknown cooking methods. You may have noticed this the last time you

made pasta or noodles.

Water is also used for fun. Water sports are a very popularrecreational activity and include activities like swimming, surfing and

waterskiing. Ice and snow are also used in ice skating, ice hockey,

skiing and snowboarding.

Water Pollution

Look at the picture. Can you identify the sources of water pollution?

Explain how these sources contribute to this problem.

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Think of a common day in your life and make drawings of situation where

you use water.


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How do you think you can reduce the amont of water you use?

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WATER PURIFICATION PROCESS

The natural water-purification process involves the action of bacteria using

oxygen to decompose organic matter. If too much waste is dumped into a

given body of water, this natural cleansing process cannot take place, or at

least does not take place fast enough.

Abstraction: water is abstracted from the source, which it is usually

located at a point that is remote from human activity which normallybrings pollution. From the source, water is carried through a pipe known as

the intake pipe which takes the water to the treatment works.

Screening: at the mouth of the intake pipe there are a series of screens

whose purpose is to prevent suspended particles from entering the system

and finding their way into the pumps..


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Coagulation removes dirt and other particles suspended in water. Alum and

other chemicals are added to water to form tiny sticky particles called

"floc" which attract the dirt particles. The combined weight of the dirt and

the alum (floc) become heavy enough to sink to the bottom during

sedimentation.

The heavy particles (floc) settle to the bottom and the clear water moves

to filtration.

The water passes through filters, some made of layers of sand, gravel, and

charcoal that help remove even smaller particles.

A small amount of chlorine is added or some other disinfection method is

used to kill any bacteria or microorganisims that may be in the water.

After disinfection the water is allowed to settle in a tank known as the

Clearwell for a specific period called the retention time during which the

chlorine does its intended work.

Water is then pumped to reservoirs which are usually located at a high

point from which it is distributed to the public.


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Section 3: HowMaterials Change


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