1. Topic 9 ReactionsofAcids

2. Titrations Burette with acid solution e.g. dilute hydrochloric acid HCl(aq) Alkali solution e.g. sodium hydroxide NaOH(aq) + indicator White tile

3. We use the following formula: P acid x V acid x C acid = P alkali x V alkali x C alkali Where P= power V= volume (l) C=Concentration

4. Power of the acid is the number of H + ions in the formula HCl has a power of 1 HNO 3 has a power of 1 H 2 SO 4 has a power of 2 Power of the alkali is the number of OH - ions in the formula NaOH has a power of 1 Mg(OH) 2 has a power of 2

5. Example 1 Q. In a titration, 25cm 3 of 0.1 mol/l NaOH was exactly neutralised by 22.2cm 3 of hydrochloric acid. Calculate the concentration of the hydrochloric acid. A. P acid x V acid x C acid = P alkali x V alkali x C alkali C acid = P alkali x V alkali x C alkali P acid x V acid

6. C acid = P alkali x V alkali x C alkali P acid x V acid C acid = 1 x 0.025 x 0.1 1 x 0.0222 C acid = 0.11mol/l Therefore the concentration of acid is 0.11mol/l.

7. Example 2 Q. What volume of 0.2mol/l sulphuric acid will exactly neutralise 25.0cm 3 of 0.5 mol/l potassium hydroxide? A. P acid x V acid x C acid = P alkali x V alkali x C alkali V acid = P alkali x V alkali x C alkali P acid x C acid

8. V acid = P alkali x V alkali x C alkali P acid x C acid V acid = 1 x 0.025 x 0.5 2 x 0.2 V acid =0.03125l Therefore 31.25cm 3 will neutralise the alkali.