block day stack your fcat website review packet on the back table. read and complete pages 214-217...
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Block Day Stack your FCAT Website Review Packet on the back
table.
Read and complete pages 214-217 in your textbook on Acids, Bases and pH (the “potential of Hydrogen”).
In your packet, read over the Acids and Bases Notes Worksheet and answer the questions at the bottom.
Pick up a lab answer sheet and put your name on it when finished. Then read over the lab instructions (green) at your table.
Acids & BasesThey are everywhere..
In your foodIn your house
EVEN IN YOU!!!!!
What is an acid? An acid is a solution that has an
excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour".
The more H + ions, the more acidic the solution.
Properties of an Acid
Tastes Sour Conduct Electricity Corrosive, which means
they break down certain substances. Many acids can corrode fabric, skin,and paper
Some acids react strongly with metals
Turns blue litmus paper red
Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml
Uses of Acids
Acetic Acid = Vinegar Citric Acid = lemons, limes,
& oranges. It is in many sour candies such as lemonhead & sour patch.
Ascorbic acid = Vitamin C which your body needs to function.
Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics.
Car batteries
What is a base?
A base is a solution that has an excess of OH- ions.
Another word for base is alkali.
Bases are substances that can accept hydrogen ions
Properties of a Base
Feel Slippery Taste Bitter Corrosive Can conduct electricity.
(Think alkaline batteries.) Do not react with metals. Turns red litmus paper
blue.
Uses of Bases Bases give soaps, ammonia,
and many other cleaning products some of their useful properties.
The OH- ions interact strongly with certain substances, such as dirt and grease.
Chalk and oven cleaner are examples of familiar products that contain bases.
Your blood is a basic solution.
pH Scale
pH is a measure of how acidic or basic a solution is.
• The pH scale ranges from 0 to 14.
Acidic solutions have pH values below 7
A solution with a pH of 0 is very acidic.
A solution with a pH of 7 is neutral.• Pure water has a pH of 7.
• Basic solutions have pH values above 7.
pH Scale
• A change of 1 pH unit represents a tenfold change in the acidity of the solution.
• For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.
Acid – Base Reactions
A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions.
Acid – Base reactions
Each salt listed in this table can be formed by the reaction between an acid and a base.
pH of Common Substances
Timberlake, Chemistry 7th Edition, page 335
Indicator
A substance or instrument that indicates if a substance is an acid, base or neutral.
Look at the list of indicators in your packet.
Reactions with indicators
Indicator Acid color
Neutral color
Base color
Phenolphthalein Colorless Faint pink Dark pink
Bromthymol blue
Yellow Green Blue
Litmus Red ----- Blue
pH paper
pH paper changes color to indicate a specific pH value.
Acids and Bases in Solution HCl + H20 H3O + + Cl- (more
hydronium ions, more acidic) NaOH in water Na+ + OH- (more hydroxide
ions, more basic) NaOH + HCl NaCl + HOH Acid + Base
yields type of salt and water NH3 + H20 NH4
+ + OH- ammonia gas + water yields ammonium and hydroxide ions
Situations in which pH is controlled
“Heartburn” Planting vegetables and flowers Fish Tanks and Ponds Blood Swimming pools
Acid Rain
Pollution in the air (sulfur dioxide, carbon dioxide, nitrogen dioxide) combines with water to form various acids.
.
Rapid changes in pH can kill fish and other organisms in lakes and streams.
Soil pH is affected and can kill plants and create sinkholes
What is a SALT? A salt is a neutral substance produced from the
reaction of an acid and a base. Composed of the negative ion of an acid and the
positive ion of a base. One of the products of a Neutralization Reaction Examples: KCl, MgSO4, Na3PO4
Neutralization Reaction
A neutralization reaction is the reaction of an acid with a base to produce salt and water.
Example
H2SO4 + NaOH NaHSO4 + H2O
Digestion and pH
Digestion-process by which foods are broken down into simpler substances.
Mechanical digestion-physical process in which food is torn apart (mouth)
Chemical digestion- chemical reactions in which large molecules are broken down into smaller molecules. (stomach and small intestines)
pH in the Digestive System
Mouth-pH around 7. Saliva contains amylase, an enzyme which begins to break carbohydrates into sugars.
Stomach- pH around 2. Proteins are broken down into amino acids by the enzyme pepsin.
Small intestine-pH around 8. Most digestion ends. Small molecules move to bloodstream toward cells that use them
mouth
esophagus
stomach
small intestine
large intestine
Digestive system
To Do:
Complete the lab.
When finished, read and complete Chapters 5-7 in textbook.
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