1. UNDERSTANDING ACIDS and ALKALIS
Intermediate 2 Chemistry
Unit 3(a)

2. Water
What do you know about the structure of water?

3. For every 560,000,000 water molecules, one will dissociate into ions.
Each molecule produces 1 H+(aq) ion and 1 OH-(aq) ion.
The number of H+(aq) and OH-(aq) ions is therefore small but EQUAL.
Equal numbers of H+(aq) and OH-(aq) ions ions means that the pH is 7.

4. What is an acid?
A solution which contains more H+(aq) ions than OH-(aq) ions.
H+(aq)
OH-(aq)

5. OH-(aq) What is an alkali?
A solution contains more OH-(aq) ions than H+(aq) ions.
OH-(aq)
H+(aq)
An alkali is a special type of base
- one which has been dissolved in water

6. What is a base?
A substance which increases the concentration of OH-(aq) ions in solution.

7. Bases
Alkalis

8. What are common lab acids?
Formula
Ions in solution
H+(aq) per formula
Strong or weak?
Hydrochloric acid
Nitric acid
Sulphuric acid
Ethanoic acid

9. What are common lab bases?
Acid
Formula
Equation for when added to water
OH-(aq) produced per formula
Strong or weak?
Magnesium oxide
Sodium hydroxide
Calcium carbonate
Ammonia