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WEEK: 5
FORMULAE AND EQUATIONS
CONTENTS:
- Chemical formulae
- Chemical equations
- Empirical and Molecular formulae
- Relative Molecular Mass and Percentage composition by mass of an element.
PERIOD 1: CHEMICAL FORMULAE
Chemical formula can be defined as a collection of two or more symbols to represent one molecule of the compound. For example, the formula of tetraoxosulphate(VI) acid is H2SO4. This formula shows that in a molecule of tetraoxosulphate(VI) acid, there are two atoms of hydrogen, one atom of sulphur and four atoms of oxygen.
The table below contain examples of compounds with their formulae
| Compounds | Formulae |
| Oxygen molecule | O2 |
| Hydrogen molecule | H2 |
| Hydrogen chloride | HCl |
| Potassium chloride | KCl |
| Magnesium tetraoxosulphate(VI) | MgSO4 |
| Hydrogen sulphide | H2S |
| Bromine Molecule | Br2 |
| Ozone | O3 |
EVALUATION
Write the chemical formulae of the following:
- Sodium oxide, Calcium oxide, aluminium oxide,
- Carbon (IV) oxide, iron (II) oxide, copper(I) oxide
- Sodium tetraoxosulphate(VI), Calcium trioxonitrate(V), magnesium trioxocarbonate(IV).
PERIOD 2: CHEMICAL EQUATIONS
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