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.