C2: Chemical Formulae

Question 1

Name the following compound:

CO₂

Answer 1

Carbon dioxide

Question 2

What does a chemical formula tell us?

Answer 2

The relative number of atoms of each element in a compound.

Question 3

Name the following compound:

CO

Answer 3

Carbon monoxide

Question 4

Identify the ratio of elements in the following compound:

Al₂O₃

Answer 4

Aluminium atoms 2: Oxygen atoms 3

Question 5

What does the _subscript tell us in a chemical formula? e.g. CO_₂_

Answer 5

How many atoms of the element are present in a compound.

e.g. CO_₂ _contains 2 oxygen atoms

Question 6

Identify the ratio of elements in the following compound:

H₂O

Answer 6

2 Hydrogen atoms: 1 Oxygen atom

Question 7

Name the following compound:

Al₂O₃

Answer 7

Aluminium oxide

Al₂O₃

Question 8

Balance this equation:

methane + oxygen –> carbon dioxide + water

CH₄ + _?_ O₂ –> CO₂ + _?_H₂O

Answer 8

Balance this equation:

methane + oxygen –> carbon dioxide + water

CH₄ + 2O₂ –> CO₂ + 2H₂O

Question 9

Complete the following equation:

_?_ Al + _?_ O₂ –> _?_ Al₂O₃

Answer 9

4 Al + 3 O₂ –> 2 Al₂O₃

Question 10

How many different elements are in each of these compounds?

1. AlCl₃
2. CaCO₃
3. K₂SO₄
4. CO

Answer 10

1. AlCl₃ - 2
2. CaCO₃ - 3
3. K₂SO₄ - 3
4. CO - 2