1. Calculating Concentrations 2
Unit 2

2. % Concentration
Definition: The percent of the solution that is solute.
Units: Mass in grams (g); Volume in millilitres (mL).
Analogy:
Your grade on a test is the percent of the test that you got correct.
There are 100 questions on the test = The solution is 100g
Your got 45 correct answers = The amount of solute is 45g
= 45% correct = 45% of solution is solute

3. How do I calculate this?
% Concentration = mass of solute x 100 Unit: %(m/v)
volume of solution
% Concentration = mass of solute x 100 Unit: %(m/m)
mass of solution
% Concentration = volume of solute x 100 Unit: %(v/v)

4. What do the following mean?
A solution labeled 5% (m/v) acetic acid contains 5 g (~5mL) of acetic acid in 95mL of water which can be expressed as:
A solution labeled 5% (m/m) acetic acid contains 5 g of acetic acid in 95 g of water which can be expressed as:

5. A solution labeled 5% (v/v) acetic acid contains 5mL of acetic acid in 95mL of water which can be expressed as:

6. Find the % Concentration for the following:
8.4 g of NaOH in 64g of solution.
18.5L of vinegar in a mL solution.
msolute= 8.4g
msolution = 64g
%C = ?
Vsolute= 18.5L = 18500mL
Vsolution = mL
%C = ?

7. Find the mass of solute in a solution where the concentration is 35%(m/m) and the mass is 150g.
msolute= ?
msolution = 150g
%C = 35%(m/m)
= 35g/100g = 0.35

8. You are given a 2. 0% (v/v) solution of NaOH. If it contains 5
You are given a 2.0% (v/v) solution of NaOH. If it contains 5.0mL of NaOH, how much solution do you have?
msolute= 5.0mL
msolution = ?
%C = 2.0%(v/v)
= 2.0mL/100mL = 0.02

9. How much water must you add to 50mL of a 20%(m/v) solution to get a final concentration of 11%(m/v)
V1 = 50mL
C1 = 20%(m/v)
V2 =?
C2 = 11%(m/v)
Note that since both my concentrations are in percent (%), I do not need to convert them to other units!
Water to add:
91mL – 50mL = 41mL

10. 6. Convert the following into g/L or %(m/v):

11. Calculating Concentrations in ppm
Unit 2

12. What are the units used to measure Concentration?
g/L
%(m/m), %(m/v), %(v/v)
ppm (parts per million)

13. Concentration in PPM 1ppm = 1ppm =
When the quantity of solute (in a total volume of solution) is extremely small, concentration is often expressed as parts per million.
ppm is a measure of 1 part solute in 1 million parts solution:
1ppm =
1ppm =

14. In aqueous solutions:
1ppm =

15. How do we calculate this?
The concentration formula does not change.
It is only the units that have changed.
Look at the values given and their units and convert to the required units.
Then you can solve your problems as you have done previously.

16. Examples:
1) 0.045g of solute was added to 1200g of solvent. What is the concentration in ppm?
Solute = 0.045g = 45mg
Solvent = 1200g = 1.2kg

17. 2). If the concentration of calcium ions in bottled water is
2) If the concentration of calcium ions in bottled water is 82ppm; what is the concentration if g/L?