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

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

Dilute (Weak) and unsaturated Concentrated (strong) Saturated

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

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.

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

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.