1. VOLUMETRIC CALCULATIONS
CHEMISTRY N5
CHEMISTRY
VOLUMETRIC CALCULATIONS

2. CHEMICAL FORMULAE & REACTION QUANTITIES VOLUMETRIC CALCULATIONS
CHEMISTRY N5
CHEMISTRY
CHEMICAL FORMULAE & REACTION QUANTITIES
VOLUMETRIC CALCULATIONS
After completing this topic you should be able to :
Calculate the concentration of a reactant using information from a titration.

3. VOLUMETRIC CALCULATIONS
TITRATIONS
The information obtained from a titration experiment can be used to calculate the concentration of one of the solutions used.

4. Volumetric Titrations
The concentration of acids/alkalis can be calculated from the results of volumetric titrations.

5. Burette
Acid solution e.g. dilute hydrochloric acid (HCl)
Conical flask with alkali solution e.g. sodium hydroxide (NaOH) + universal indicator
White tile

6. Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
P= power V= volume in litres C= concentration
Power of an acid is the number of H+ ions.
For HCl, p=1
For H2SO4, p=2
For HNO3, p=1
Power of an alkali is the number of OH- ions.
For NaOH, p=1
For Ca(OH)2, p=2
For Al(OH)3, p=3

7. Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
Example: 20 cm3 of 0.1 mol l-1 potassium hydroxide solution (KOH) was neutralised by 15.4 cm3 of sulfuric acid (H2SO4).
Calculate the concentration of the sulfuric acid.
Step One: Record what information you know about the acid and the alkali.
ACID (H2SO4)
ALKALI (KOH)
P = 2
P = 1
V = L
V = 0.02 L
C =
C = 0.1 mol l-1
Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
Step Two: Write out the PVC formula, and fill in the values that you know. Multiply out to simplify, then solve the equation to give a value for C.
2 x x Cacid = 1 x 0.02 x 0.1
x Cacid = 0.002
Cacid = 0.002/
Cacid = mol l-1

8. Example 1 Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
In a titration 10cm3 of sodium hydroxide solution with a concentration of 0.2 mol l-1 was neutralised by 25 cm3 of dilute hydrochloric acid.
Calculate the concentration of the acid solution in moles per litre.
Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
1x x Cacid = 1 x 0.01x 0.2
1x x Cacid = 1 x 0.01x 0.2
0.025 x Cacid = 0.002
Cacid = / 0.025
Cacid = mol l-1

9. Example 2 Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
What volume of 2M sodium hydroxide will be required to neutralise 40cm3 of 2M sulphuric acid?
Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
2 x 0.04 x 2 = 1 x Valkali x 2
0.16 = Valkali x 2
Valkali = 0.16 / 2
Valkali = 0.08 litres
Valkali = 80 cm3

10. Example 3 Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
What volume of 1M sulphuric acid will be needed to neutralise 2 litres of 0.1M potassium hydroxide?
Pacid x Vacid x Cacid = Palkali x Valkali x Calkali
2 x Vacid x 1 = 1 x 2 x 0.1
Vacid x 2 = 0.2
Valkali = 0.2 / 2
Valkali = 0.1 l
Valkali = 100 cm3