1. What is the concentration of a solution?
A dilute solution is a weak solution
A weak solution has a small amount of dissolved solute
Ex: chocolate milk with only 1 tsp of chocolate syrup
The solution appears light in color
A concentrated solution is a strong solution
A strong solution has a large amount of dissolved solute
Ex: chocolate milk with 5 tsp of chocolate syrup
The solution appears darker

2. Unsaturated vs. Saturated Solutions
An unsaturated solution is a solution that contains less solute than it can hold at a given temperature
A saturated solution is a solution that contains all the solute it can hold at a given temperature
Temperature is important because a change in heat changes how spread apart molecules are and this changes how well a solute can dissolve

3. Dilute (Weak) and unsaturated
Concentrated
(strong)
Saturated

4. How to make a super-saturated solution
A super-saturated solution is a solution containing more solute than it can normally hold at a given temperature
A supersaturated solution can be made by heating a saturated solution
When heated, the particles spread apart, allowing the solution to hold more solute, and it becomes unsaturated
If more solute is added, when the solution cools, it will contain more solute than it would normally hold at the cooler temperature
It is now a super-saturated solution
This process is how crystals are formed

5. Sugar (solute) Dissolved Water (solvent)
Saturated solution: no more of the solute dissolves in the solvent at that particular temperature
Unsaturated solution: the solute dissolves completely in the solvent at a particular temperature
Supersaturated
Solution
Added heat
On cooling the solution, the excess solute crystallizes out of the solution.
At higher temperatures, more of the solute dissolves in the solvent because heat causes particles to spread out and make more room.

6. The Rate of Solubility
Solubility is a solution’s ability to dissolve more solute
Once a solution reaches the point of saturation, there is no room for more solute to dissolve
Any added solute would simply sink to the bottom
However, heating a saturated solution causes it to become unsaturated
The higher the temperature, the more solute a solvent can hold; increasing its solubility
Heating causes particles to move further apart, so that more solute can dissolve

8. Understanding the Solubility Graph
Sucrose, Sodium chloride, Potassium chloride, and calcium carbonate are all solutes that dissolve in water
The graph shows how each substance’s solubility changes as the temperature increases
Sucrose becomes very soluble as heat is added
Sucrose’s particles are not very dense, so they spread out quickly, making more room for more solute to dissolve
Calcium carbonate did not increase its solubility much
Calcium carbonate’s particles are very dense and do not readily spread apart with heat.