Aqueous Solutions

Question 1

The 3 main ways substances dissolve in water
3 marks

Answer 1

1. Decomposition
2. Ionisation
3. Dissociation

Question 2

What is decomposition
3 marks

Answer 2

• Particles spread evenly throughout the solution.
• Physical process, because it does not involve any chemical changes.
• Can be separated by letting the water evaporate.

Question 3

What is Ionisation

Answer 3

The reactions of a molecular compound with water to form
ions.

• The ions spread evenly throughout the solution.
• Opposite charged dipoles of the ions attract each other.
• It is a chemical process because new products are formed from the reagents.

Question 4

What is Dissociation
6 marks

Answer 4

The breakdown of an ionic compound into its
constituent ions.

• The ions spread evenly throughout the solution.
• Cations (+ ions, Na+) and anions (– ions, Cℓ-) are formed.
• Cations are surrounded by the negative pole of the water molecules (O – oxygen
side).
• Anions are surrounded by the positive pole of the water molecules (H –
hydrogen side).
• Note that water is not added to the reaction but is shown above the arrow.

Question 5

What is a Covalent reaction
Where is the H20

Answer 5

Between non-metals
H20 in the reaction

Question 6

What is a Ionic reaction
Where is the H20

Answer 6

Between a metal and a non-metal
H20 on the line