Reactions of Acids Acids can react with a variety of different chemicals. These are normally NEUTRALISATION REACTIONS We have looked at ACIDS + ALKALIS so far. ALKALIS are part of a much larger group of chemicals which neutralise acids called BASES.

Reactions of Acids There are 4 different types of BASES to investigate: (1)Metal hydroxides (alkalis) (2) Metal Oxides (3) Metal Carbonates (4) Metals

(1) Acids with Metal Hydroxides Experiment: Investigating acids & alkalis Acid + Alkali Salt + Water Notes: Metal Hydroxides (alkalis) are the soluble form of bases H + from the acid combine with the OH - from the alkali to make water The salt forms from the NEGATIVE ION from the acid and the POSITIVE ION from the alkali This reaction gives out heat (EXOTHERMIC)

(1) Acids with Metal Hydroxides What is a SALT? A salt is the product of a neutralisation reaction They are substances where the H + ion of the acid has been replaced by a POSITIVE METAL ION (or Ammonium)

Starter Question What is the NAME of the salt that would be formed from the reaction of: (i) Hydrochloric acid and Calcium Hydroxide (ii) Sulphuric acid and Magnesium Hydroxide (iii) Nitric acid and Ammonium Hydroxide

(2) Acids with Metal Oxides Experiment: Investigating acids & metal oxides Acid + Metal Oxide Salt + Water Notes: All metal oxides react with acids Again the salt is formed from the acid where the H + ion has been replaced with the POSITIVE METAL ION from the metal oxide

(3) Acids with Metal Carbonate Experiment: Investigating acids & metal carbonates Acid + Metal Salt + Water Carbonate + Carbon Dioxide Notes: Metal Carbonates all contain the carbonate (CO 3 2- ) ion CARBON DIOXIDE is given off Carbon dioxide can be detected as it turns LIMEWATER CLOUDY

(4) Acids with Metals Experiment: Investigating acids & metal carbonates Acid + Metal Salt + Hydrogen Notes: The Group 1 & 2 metals will also react but is dangerous! Hydrogen gas is produced As with all other reactions, a SALT is formed

Summary of Acid Reactions Acid + Metal Salt + Water Carbonate + Carbon Dioxide Acid + Metal Oxide Salt + Water Acid + Metal Salt + Hydrogen Acid + Alkali Salt + Water

Acid Rain Acid rain forms from two main pollutant gases dissolving in atmospheric water (rain). The two gases are: Sulphur Dioxide Oxides of Nitrogen

(1) Sulphur Dioxide Sulphur is found as an impurity in fossil fuels. When it burns in oxygen it produces SULPHUR DIOXIDE. This then dissolves in atmospheric water and falls as ACID RAIN.

(2) Oxides of Nitrogen (NO, NO 2 ) The spark plug in a car provides enough energy for nitrogen and oxygen to react. This creates OXIDES of NITROGEN – these are normally shown as NO x (eg NO, NO 2 ). These oxides can dissolve in atmospheric water (clouds) and fall as ACID RAIN N2N2 O2O2 NO 2 NO NO 2 NO NO 2