1. Solution Concentrations

2. Solution = solute + solvent
Percent by Mass (m/m)
Mass of solute
Mass of solution
×100
Solution = solute + solvent

3. Water is always a solvent!!!
Example 1
solute
solvent
An aquarium must contain 13.6 g NaCl per g of water. What is the percent by mass (m/m) of NaCl in the solution?
Water is always a solvent!!!
Solute:13.6g (smaller #)
Solvent: 100.0g (larger #)
Solution: 113.6g
Mass of solute
Mass of solution
×100 +
13.6
113.6
×100 = 11.97% ≈ 12.0%

4. Example 2 − solute 650.0 ×100 = 1.25% Solute = 8.13g
You have a 650.0g KCL solution. If the percent by mass is 1.25% (m/m), how many grams of solute is in the solution? How many grams of solvent are in the solution?
Then remember: solute + solvent = solution
and solve for solvent
First find solute:
Solution: 650.0g
Solute: 8.13g
Solvent = g ≈ 642g
solute
650.0
×100 = 1.25% −
Solute = 8.13g

5. Percent by Volume (v/v)
Volume of solute
Volume of solution
×100
Solution = solute + solvent

6. Example 3
What is the percent by volume of ethanol in a solution that contains 45mL of ethanol dissolved in 145mL of water?
solute
solvent
Then remember: solute + solvent = solution
and solve for solvent
Solute: 45mL (smaller #)
Solvent: 145mL (larger #)
Solution: 190mL 45
190
×100 = 23.68% ≈ 24% +

7. Means dissolved in water; water is the solvent
Example 4
If you have mL of a 35.0% aqueous solution of ethanol, what volume of ethanol and water are in the solution?
First find solute:
Solution: 200.0mL
Solute: 70.0mL
Solvent = 130.0mL
≈ 130. or 1.3×102 mL
solute
200.0
×100 = 35.0% −
Solute = 70.0mL

8. Parts Per Million (ppm)
Solute
Solution
×106
1 ppm = 1mg/L

9. Example 5
If 25 grams of a chemical is dissolved in 75 grams of water, what is the concentration of the chemical in parts per million (ppm)?
Solute: 25g (smaller #)
Solvent: 75g (larger #)
Solution: 100g + 25
100
×106 = 250,000 or 2.5×105 g

10. Example 6
Suppose 17 grams of sucrose is dissolved in 183 grams of water. What is the concentration of sucrose in ppm?
Solute: 17g (smaller #)
Solvent: 183g (larger #)
Solution: 200g + 17
200
×106 = 85,000 or 8.5×104 g

11. So change the mL into L and the g into mg
Example 7
150 mL of an aqueous sodium chloride solution contains g NaCl. Calculate the concentration of NaCl in parts per million (ppm). Remember 1ppm = 1 mg/L
So change the mL into L and the g into mg
0.0045g 1000mg 1000mL
150mL g L
= 30 mg/L = 30 ppm

12. Example 8 Convert 0.0035% NaCl by mass into parts per million of NaCl.
* Think of % like your grade on a test; % means out of 100
0.0035
100
×106 = 35ppm