Acids and BasesHolt: Chapter 15, Sections 2 and 3Fusion: Lesson 6 (starts on p 190)

Acids

• An acid is any compound that increases the number of hydronium ions (H+) when dissolved in water• Acids typically begin with hydrogen, H. • Examples: H2SO4, HCl

Acids and their properties

• Sour taste ex: citric acid (we NEVER taste in a lab)• Corrosive- they destroy body tissue, clothing, and many other things• Can be poisonous• Reacts with some metals to produce hydrogen gas• Can conduct electric current ex: battery acid• Acid turns blue litmus paper red• What is litmus paper? • An indicator. An indicator is a substance that changes color in the presence of an acid or base. Litmus paper is NOT the only indicator.

Uses of acids

• H2SO4 is sulfuric acid. Is the most widely made industrial chemical in

the world. Used to make paper, paint, detergent and fertilizers.• Used in swimming pools to kill algae• HCl used in your stomach to digest food• Citric acid and ascorbic acid are in orange juice• Carbonic acid and phosphoric acid are in soda

Bases

• A base is any compound that increases the number of hydroxide ions, (OH- ) when dissolved in water.• Most bases end with OH-

• Examples: NaOH, Ca(OH)2

Bases and their properties

• Bitter taste• Slippery feel• Many bases are corrosive• Bases turns red litmus paper blue• Conduct electric current

Uses of bases

• NaOH (sodium hydroxide) is used to make soap and paper, oven cleaners and products to unclog drains• Ca(OH)2 (calcium hydroxide) is used to make cement and plaster• Ammonia is found in household cleaners and to make fertilizer• Magnesium hydroxide and aluminum hydroxide are used in antacids

to treat heartburn.

Strengths of acids and bases

Acids• Strong acids have additional H+

• All of the acid’s molecules break apart• Examples of strong acids: H2SO4

(sulfuric acid), H2CO3 (carbonic acid), H3PO4 (phosphoric acid)

Bases• Strong bases have additional OH-

• All of the base’s molecules break apart• Examples of strong bases:

Ca(OH)2 (calcium hydroxide), Ba(OH)2 (barium hydroxide)

Neutralization

• The reaction between acids and bases is a neutralization reaction.• React to form water (which is neutral) and a salt.• A salt is an ionic compound formed from the positive ion of a base

and the negative ion of an acid.• Salts are a large group of compounds; not just table salt!

pH scale

• Indicators are used to identify whether a solution contains an acid or a base.• A pH scale is used to describe how acidic or how basic a solution is.• pH is a measure of the hydronium ion concentration.• pH of 7 is neutral; pure water• pH of less than 7 is acidic• pH of greater than 7 is basic

pH values of common materials