8.5
Solubility and Saturation
The Degrees of Saturation:
Solubility is the quantity of
that can dissolve in a given quantity of
. Quantitatively, solubility is expressed as the
mass of solute that can be dissolved per
g of
at a given temperature.
Define the following terms:
Saturated Solution:
Unsaturated Solution:
Supersaturated Solution:
Solubility Curves
Y-axis:
Solubility of
substance
(g/100 g H2O)
Substances: Compound
being dissolved in water
(H2O)
X-axis: Temperature (Celsius)
How does the solubility of sucrose (table sugar) change as the temperature increases?
What is a solubility curve?
Intepereting a Solubility Curve
Each point on the solubility curve shows how many grams can be dissolved at a specific temperature.
Each line shows how much substance can dissolve as a function of the temperature of the solution.
Example:
Answer the following questions:
How many grams of potassium chloride (KCl) can dissolve in 100 grams of water at 20°C?
How many grams of potassium nitrate (KNO3) can dissolve in 100 g of water at 40°C?
How many grams of sodium chloride (NaCl) can dissolve in 100 g of water at 100°C?
How many grams of potassium chlorate (KClO3) can dissolve in 200 g of water at 80°C?
At what temperature can 75 grams of potassium nitrate (KNO3) dissolve in 100 g of water?
At what temperature can 30 grams of potassium chloride (KCl) dissolve in 100 g of water?
How we numerically describe saturation:
Saturated: solute = solubility
Unsaturated: solute < solubility
Supersaturated: solute > solubility
Sample Problem (see p.395): A potassium sulfate solution, K2SO4 (aq), containing 11.8 g/100 g H2O at
20 °C, is warmed to 60°C. What additional mass of potassium sulfate is required to saturate this
solution at 60°C?
Solubility of Gasses
What do you notice about the solubility of oxygen as temperature increases?
Homework:
p. 395 Practice #1-3
p. 137 #1-4, 6