1.1 Formulae and Equations

WJEC A-Level Chemistry

Formulae of Sulfur Dioxide

Formulae of Sulfur Dioxide

SO₂

Formulae of Methane

CH₄

Formulae of Hydrochloric Acid

HCl

Formulae of Sulfuric Acid

H₂SO₄

Formulae of Nitric Acid

HNO₃

Formulae of Ammonia

NH₃

Formulae of Ammonium Chloride

NH₄Cl

Formulae of Sodium Hydroxide

NaOH

Formulae of Sodium Chloride

NaCl

Formulae of Sodium Carbonate

Na₂CO₃

Formulae of Sodium Hydrogencarbonate

NaHCO₃

Formulae of Sodium Sulfate

Na₂SO₄

Formulae of Calcium Hydroxide

Ca(OH)₂

Formulae of Calcium Carbonate

CaCO₃

Formulae of Calcium Chloride

CaCl₂

Formulae of Copper (II) Oxide

CuO

Formulae of Copper (II) Sulfate

CuSO₄

How to find charge of ion?

Use group number

e.g. group 7 has charge of ^-

What is a redox reaction?

A reaction where one substance is reduced and another is oxidised.

What is oxidation?

• gain of oxygen

• loss of hydrogen

• loss of electrons

What is reduction?

• loss of oxygen

• gain of hydrogen

• gain of electrons

What is a reducing agent?

• reduce other species

• give electrons

• are themselves oxidised

What is a oxidising agent?

• oxidise other species

• accept electrons

• are themselves reduced

What is the oxidation of an uncombined element?

0

e.g. O₂ = 0

What is the oxidation of a simple ion?

Charge of the ion

e.g. O^2- = -2

What is the oxidation of a compound?

The sum must equal 0

What is the oxidation of group 1 and 2 metals in a compound?

Same as their group number

e.g. BaSO₄ = Ba=+2

What is the oxidation of a complex ion?

The sum must equal the charge

e.g. CO₃^2- = C=+4, O=-2

What is the oxidation of Hydride?

H = -1

What is the oxidation of Fluorine?

F = -1

What is the oxidation of Peroxide?

O = -1

Steps to work out ionic equations

1. word equation

2. balanced symbol equation

3. balanced ionic equation (usually for precipitate (s) )

4. spectator ions