1. Solubility and Solubility Curves
Solubility Notes
Solubility and Solubility Curves

2. Solubility
The solubility of a substance is determined by the mass of solute needed to make a saturated solution in 100 g (100 ml) of water at a certain temperature.
Saturated – The total amount (mass) of solute that can be dissolved into solution at a certain temperature
All points on the “solubility curve”
Also known as the solution equilibrium line

3. Solubility
Unsaturated: any point below the “solubility curve” of a substance at a certain temperature.
Therefore, more solute can dissolve
Supersaturated: any point above the “solubility curve” of a substance at a certain temperature
Saturated: any point on the “solubility curve”

4. Solubility Chart
The amount in grams is plotted on a graph based on the temperature.
The maximum amount of a solute dissolved in 100g of water is tested at four different temperatures.
Temp (°C)
Dissolved Solute (g)
23.1 20
32.0 60
61.8
100
114.0

5. Solubility Chart
Then the data points are connected by a line or curve.
The curve represents the maximum amount of a solute dissolved in 100g of water for ALL temperatures between 0°C and 100°C.
Q: Why is the scale only between 0°C and 100°C?
A: Solutes dissolve in LIQUID water

6. Solubility Curve At 40°C, 100g of water can dissolve how much solute?
Saturation at 40°C with 45 grams of solute

7. Solubility Curve Will 50 grams dissolve in 100g of water at 75°C?
For any point
below the solubility curve
the solution is UNSATURATED
Will 50 grams dissolve in 100g of water at 75°C?
Yes, it can. Will the solution be saturated, unsaturated, or supersaturated with 50 grams at 75°C?

8. Solubility Curve For any point above the solubility curve the
solution is
SUPERSATURATED
Is a solution with 70g of solute dissolved at 40°C saturated, unsaturated, or supersaturated?

9. Solubility Questions
1. At 60°C, 38g of solute is dissolved in 100g of water. What is the name of the solute?
2. If 50g of KCl are dissolved in 100g of water, at 80°C, is the solution saturated, unsaturated, supersaturated?
3. What is the solubility of KNO3 at 45°C in 200g of water?
4. What is the solubility of KCl at 80°C in 150g of water?