Millilitres in every 100 mL
Volume by volume percentage (% v/v).
Two liquids
Perfumes, cosmetics, vinegar and pesticide sprays are made by mixing two liquids that mix completely.
How would you measure how much of one liquid is in the mixture?
What this lesson covers
The idea
Volume by volume percentage (% v/v) = (volume of solute ÷ volume of solution) × 100, the millilitres of solute in 100 mL of solution; it is applied when two miscible liquids are mixed.
Two liquids
Perfumes, cosmetics, vinegar and pesticide sprays are made by mixing two liquids that mix completely.
How would you measure how much of one liquid is in the mixture?
- By its volume in millilitres
- By its colour
- By counting drops of water only
Make the spray
Add liquid pesticide, make the spray up to the mark, and stir. Make 1 % twice.
% v/v
Volume by volume percentage (% v/v) = (volume of solute ÷ volume of solution) × 100. It tells how many millilitres of solute are in 100 mL of the solution. It is used when two miscible liquids are mixed, for example in perfumes, cosmetics and vinegar.
Example 5.3. 1 mL of liquid pesticide is mixed with enough water to make 100 mL of spray for a rice crop. Percentage = (1 mL ÷ 100 mL) × 100 = 1 % v/v.
Notes
% v/v = (volume of solute ÷ volume of solution) × 100: the millilitres of solute in 100 mL of solution. Used for two miscible liquids.
Check yourself
2 mL of liquid pesticide is made up to 200 mL of spray. What is the % v/v?
Answer: 1 % v/v
(2 mL ÷ 200 mL) × 100 = 1 % v/v.
10 mL of a liquid is mixed with water to make 100 mL of solution. What is the % v/v?
Answer: 10 % v/v
(10 mL ÷ 100 mL) × 100 = 10 % v/v.
% v/v is used when…
Both the solute and the solution are measured in…
- a solid is weighed on a balance. That suits % m/m.
- a gas is dissolved in a solid. % v/v is for two liquids.
- two miscible liquids are mixed — correct. Yes.
- grams (mass). Mass is used in % m/m.
- millilitres (volume) — correct. Yes.
- degrees Celsius. That measures temperature.