Reactions of Acids

Reactions of Acids

Definition of Acids

• Acids are substances that can donate a proton (H+ ion) when they react.
• They turn blue litmus paper red, have a sour taste, and react with bases and certain metals to produce salts.

Reaction with Metals

• Acids react with most metals to produce a salt and hydrogen gas.
• For example, when hydrochloric acid reacts with magnesium, magnesium chloride and hydrogen are produced: 2HCl(aq) + Mg(s) -> MgCl2(aq) + H2(g).

Reaction with Bases

• An acid-base reaction is also known as a neutralisation reaction. The result of this reaction is a salt and water.
• When sulfuric acid reacts with sodium hydroxide (a base), it forms sodium sulfate and water: H2SO4(aq) + 2NaOH(aq) -> Na2SO4(aq) + 2H2O(l).

Reaction with Carbonates

• Acids react with carbonates to produce a salt, carbon dioxide and water. This is an acid-carbonate reaction.
• When hydrochloric acid reacts with calcium carbonate, calcium chloride, carbon dioxide and water are produced: 2HCl(aq) + CaCO3(s) -> CaCl2(aq) + CO2(g) + H2O(l).

Testing for Carbon Dioxide

• The test for carbon dioxide is that it turns limewater cloudy when bubbled through it.

Salts

• Any compound formed when hydrogen in an acid is wholly or partially replaced by a metal or ammonium ions is called a salt.
• The name of a salt has two parts. The first part comes from the metal, or ammonium ion. The second part comes from the acid: chloride (from hydrochloric acid), sulfate (from sulfuric acid), nitrate (from nitric acid).