How do solutes affect a solution’s boiling point? By adding more solute to a solution, the boiling point of that solution increases Boiling point is the temperature at which a liquid changes to a gas Pure Water's boiling point is 100 °C If salt is added to water, the water will boil at a higher temperature – about ½ a degree for every 58 grams added This is known as boiling point elevation Boiling point elevation is raising the boiling point of a liquid solvent by adding solute This occurs because the density has changed and it becomes more difficult for the substance to boil. Examples: Drivers add anti-freeze to their car’s cooling system to prevent overheating in the summer Chefs add salt to boiling water so food can cook faster

As the amount of dissolved solute increases, the boiling point of the solution increases 0 5 10 15 20 25 Grams of Dissolved Sugar

How do solutes affect a solution’s freezing point? By adding more solute to a solution, the freezing point of that solution decreases Freezing point is the temperature at which a liquid changes to a solid Pure water's freezing point: 0° C / Seawater freezes at about -2.2°C Freezing point depression is lowering the freezing point of a liquid solvent by adding solute This occurs because the density increases, making it more difficult for the solution to freeze. Examples: Anti-freeze also works to prevent the liquids in a car’s engine from freezing in winter Fish have solutes dissolved into their blood to prevent them from freezing in harsh temperatures

Why do we throw rock salt onto icy roads? Rock salt is placed onto icy roads because salt lowers the freezing point of the ice. As ice melts, the salt dissolves in water, making salt water, which has a lower freezing point than pure water The temperature must get lower than 0° C before the salt freezes, therefore ice does not form as fast. The rocks also help reduce friction, and prevent slipping on the ice.

As the amount of dissolved solute increases, the freezing point of the solution decreases Pure Water Grams of Dissolved Sugar

Boiling point Elevation: When more solute is dissolved into the solvent, the boiling point of the solution increases Freezing Point Depression: When more solute is dissolved into the solvent, the freezing point of the solution decreases