Acids and Bases An Introduction

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

Common Acids and some everyday uses

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

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

Common household bases and some everyday uses

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

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)