C2.6

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Acids and Bases:

Hydrochloric acid HCL Chlorides

Sulphuric acid H2SO4 Sulphates

Nitric acid HNO3 Nitrates

Acids give H+ in water

Bases accept H+

Alkalis are soluble bases and give OH- in water

Bases include metal oxides, metal hydroxides and metal carbonates

Hydrochloric acid - HCl

Sulphuric acid - H2SO4

Nitric acid - HNO3

Sodium hydrocise - NaOH

Potassium hydroxide - KOH

Ammonia - NH2

Reactions occur when particles collide with sufficient energy. The maximum amount of energy required for particles to react on collision is called the activation energy.

Acid + metal - Salt + Hydrogen

Acid + base - Salt + Water

Acid + carbonate - Salt + H2O +CO2

Neutralisation:

An acid can be neutralised by a base

H+ (aq) + OH- (aq) - H2O (l)

Examples:

Calcium hydroxide + Hydrochloric acid - Calcium Chloride

Magnesium oxide + Nitric acid - Magnesium nitrate

Calcium carbonate + Sulphuric acid - Calcium sulphate

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Salts:

Metals can be reacted with an acid until all the metal is used up.

Excess metal can be filtered off

Water can be evaporated from the solution and the salt left to crystallise

Disadvantages: not all metals are suitable; some are too reactive and others aren't reactive enough

acid + metal - salt +hydrogen

acid + carbonate - salt +h2o + co2

acid + base - salt + water

acid + alkali - salt + water

Ammonia dissolves in water to produce an alkaline solution. It is used to produce ammonium salts. Ammonium salts are important as fertilisers.

Place a known volume of alkali in a beaker

Add an indicator

Add acid drowse until the solution is neutral. Record the amount of acid required

Mix the same volume of alkali and acid, evaporate off some of the water and leave to crystallise.

Insoluble salts can be made by mixing appropriate solutions of ions so that a precipitate is formed

The precipitate can be separated using filter paper, washed with distilled water and left to dry.

All nitrates are soluble, all sodium salts are soluble

Precipitation can be used to remove unwanted ions from solutions, for example in treating water fir drinking or in treating effluent.