C3.3

Oxidation is loss of electrons.

Reduction is the gain of electrons.

Oxidation is when a substance gains oxygen

Reduction is when a substance loses oxygen

The substance that gets reduced is the oxidising agent.

The substance that gets oxidised is the reducing agent.

An acid is a substance that releases H+ ions when dissolved in water to make an aqueous solution. HCl -> H+ + Cl-

A base is a substance that can neutralise acids. If a base can dissolve inn water it is an alkali. Alkali’s release OH- ions in the water. NaOH -> Na+ + OH-

The PH scale describes the relative acidity or alkalinity. PH < 7 = acidic PH = 7 = neutral PH > 7 = alkaline

Strong acid PH-0, strong acid PH-14

Neutralisation is the reaction between an acid and a base, or an alkali to form salt and water only. The salt depends upon the acid or base used.

acid + base –> salt + water

In a neutralisation reaction the PH becomes 7, but may become more acidic or alkali depending on how much of each product is added.

First part comes from the metal in the base or alkali exception is when ammonia or ammonium carbonate is used resulting in ammonium. Second part of the name comes from the acid.

HCl - chloride Nitric acid - nitrate Sulphuric acid - sulphate Phosphoric acid - Phosphate

The H+ and OH- ions react to create water. H+ + OH- -> H2O

The salt produced depends on the other ions present e.g. Na+ and OH-

A metal hydroxide and hydrogen form

Carbonates are ionic compounds that contain CO3 2-. Carbonates react with acids to form a salt, plus water + CO2.

acid + carbonate -> salt + water + carbon dioxide

acids + metal -> salt + hydrogen

A dilute acid contains a low ratio of acid to volume of solution.

A concentrated acid contains a high ratio of acid to volume of solution.

A weak acid is partially ionised (only a small fraction of their molecules release H+ ions)