SCH3U1
Dilution of Solutions
Often it is necessary to dilute prepared solutions to different concentrations in the lab.
This may be because the solute is itself a liquid (e.g. alcohol) or an aqueous solution (e.g.
acids), or because it is more convenient to keep a small volume of a more concentrated
“stock”solution, and prepare diluted solutions as they are needed. Dilution calculations
are therefore commonly encountered.
c
Dilution problems can be solved in 2 ways:
Method 1:
(i) calculate moles of solute (n = c V) required in the dilute solution
(ii) calculate the volume of concentrated solution required (V = n/c).
Method 2:
Since the number of moles of solute is equal in the diluted and concentrated solutions,
n1 = n2; therefore:
c1V1  c2V2
This can be solved for the unknown quantity.
Sample Problems:
1. a) Concentrated sulfuric acid has a concentration of 18 mol/L. What volume should be used
to prepare 2.00 L of 1.00 mol/L sulfuric acid?
b) How much water should be added?
a)
b)
2. If 500 mL of water is added to 100 mL of a 0.750 mol/L solution, what would be the
concentration of the resulting solution?
n
V
Dilution Problems
1. What volume of a 6.0 mol/L sulfuric acid solution would be required to make 500 mL of 0.24
mol/L sulfuric acid?
2. a) What volume of 6.0 mol/L hydrochloric acid would be diluted with water to prepare 1.0 L
of 1.2 mol/L hydrochloric acid?
b) How much water should be added?
3. What volume of 17.2 mol/L acetic acid should be taken and diluted with water to make 1.00
L of 0.100 mol/L acetic acid?
4. What volume of concentrated 14 mol/L ammonia (NH3) should be measured out and diluted
with enough water to make 5.0 L of a 0.10 mol/L solution?
5. What would be the concentration (in mol/L) of a solution made by adding 200 mL of water
to 50 mL of a 5.0 mol/L solution of potassium chloride?
6. What volumes of 12.0 mol/L potassium nitrate solution and water would have to be mixed in
order to produce 300 mL of a 8.00 mol/L solution?
7. If 150 mL of water are added to 250 mL of a 0.24 mol/L solution of hydrochloric acid what
will be the concentration in mol/L?
8. The cafeteria decides to save money by using concentrated acetic acid (CH3COOH at 17.5
mol/L) and diluting it with water to produce vinegar (5.00% m/v acetic acid).
a) What is the concentration of vinegar in mol/L?
b) What volume of vinegar can the cafeteria produce from a 4.00 L jug of concentrated acetic
acid?
c) How much water would they need to add to the concentrated acetic acid?
Solutions to Dilution of Solutions
1. 20 mL
2. a) 0.20 L b) 0.8 L
3. 0.00581 L
4. 0.036 L
5. 1.0 mol/L
6. 200 mL KNO3 solution + 100 mL water
7. 0.15 mol/L
8 a) 0.833 mol/L
b) 83.9 L
c) 79.9 L water