1. Acids and Bases
An Introduction

2. Acids
A group of chemical compounds (more than one element) with similar properties
Solutions of acids have a sour taste
Can be classified as strong or weak
Sulfuric acid (H2SO4) is a strong acid used in car batteries
Hydrochloric acid (HCl) is a strong acid used to clean mortar from bricks
HCl also used for digestion in stomach in weaker solution

3. Common Acids and some everyday uses

4. Problems with acids
Can cause contamination in waterways and threaten fish
Acid rain causes soils to become ‘sour’ and stunts plant growth
Steel and marble buildings are corroding faster than ever, due to increased levels of acidity of atmosphere

5. Bases Chemical compounds that are the opposite of acids
Bases that are soluble in water are called alkalis
Have a bitter taste and a soapy feel
Commonly used in the home as cleaning agents
Sodium hydroxide (NaOH- caustic soda) is a strong base used to make soaps, drain cleaner and oven cleaner
A concentrated solution is corrosive (will burn the skin) and poisonous

6. Common household bases and some everyday uses

7. Reactions of acids and bases
When acids are added to bases, they cancel each other out
Called a neutralisation reaction
Example:
Indigestion, it is due to too much acid in the stomach; Magnesium hydroxide, Mg(OH)2 is used to counteract the stomach acids
Bee stings contain acid and can be treated with a base, such as ammonia
Wasp stings contain a base, so they are better treated with an acid such as vinegar

8. Reactions of acids and bases
In any neutralisation reaction, the acid and base combine to produce a salt and water
acid + base → salt + water
Eg. When hydrochloric acid reacts with sodium hydroxide, sodium chloride and water are formed.
Hydrochloric acid + sodium hydroxide → sodium chloride + water
(acid) (base) (salt) (water)