Janine Pauline S. SierdaChemistry Teacher

LET’S PRAY…LET’S PRAY…

OBJECTIVES

Explain the Colligative properties of solutions;

Relate the importance of these to human daily living.

LET’S DEFINE…

Vapor Pressure Vapor Pressure is the pressure of the vapor resulting from evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container.

Freezing Point Freezing Point is the temperature at which a liquid becomes a solid.

  Boiling Point Boiling Point is the temperature at which a liquid

boils at a fixed pressure, especially under standard atmospheric conditions.

  TemperatureTemperature is a measure of the average kinetic

energy (KEavg) of the particles of a substance.

non-volatile solute (the salt, for example) hasn't got any tendency to form a vapour at the temperature of the solution/

ACTIVITYACTIVITY

RUBRICS: Accuracy – 40% Cooperation – 10%. Discipline – 20%

Clarity of the output – 30% Total 100%

PRESENTATION FORMAT Group # ____ Title of Activity: Materials: Procedure: Data: Illustrations: Point of Discussion / Observation/s: Conclusions:

ACTIVITYACTIVITY

COLIGATIVE PROPERTIESCOLIGATIVE PROPERTIES are characteristics which depends primarily

upon the number of dissolved particles than the nature of the particles.

There are four colligative properties of solution these are:

Freezing Point LoweringOsmotic Pressure /OsmosisBoiling Point ElevationVapor Pressure Lowering

Freezing Point Lowering

Freezing point occurs when the freezing point of a liquid is lowered by adding another compound to it. The solution has a lower freezing point than that of the pure solvent.

For example, the freezing point of seawater is lower than that of pure water. The freezing point of water to which antifreeze has been added is lower than that of pure water.

salting icy roadsantifreeze

How much should be the lowering of the freezing point of the solution?

Osmotic Pressure

It arises when two solutions of different concentrations, or a pure solvent and a solution, are separated by a semi-permeable membrane.

A semipermeable membrane allows the passage of solvent molecules but blocks the passage of solute molecules.

Boiling Point Elevation Boiling point elevation occurs when the

boiling point of a solution becomes higher than the boiling point of a pure solvent.

The temperature at which the solvent boils is increased by adding any non-volatile solute. A common example of boiling point elevation can be observed by adding salt to water. The boiling point of the water is increased.

Vapor Pressure Lowering The vapor pressure of a liquid is the equilibrium

pressure of gas molecules from that liquid (i.e., the results of evaporation) above the liquid itself.

Vapor pressure: is the pressure exerted by a vapor that is in dynamic equilibrium with its liquid in a closed system.A solution that contains

a solute that is nonvolatile (not easily vaporized) always has a lower vapor pressure that the pure solvent.

This is true because in This is true because in a solution, solute a solution, solute particles reduce the particles reduce the number of free solvent number of free solvent particles able to particles able to escape the liquid.escape the liquid.

Pure water - microscopic view.

NaCl solution - microscopic view.

ROULT’S LAW

states that “lowering of the favor pressure by non-volatile solute is directly proportional to the concentration or amount of solute in the solution”

How will you relate these How will you relate these colligative properties of colligative properties of

solution in our daily living? solution in our daily living?

How will you relate the How will you relate the colligative properties to colligative properties to

human health and activities?human health and activities?

QUIZ:

Identify the following: _____________ 1 . The temperature where the vapor

pressure of a solution equals the atmospheric pressure.

_____________2. The movement of solvent particles from concentrated particles area to less concentrated area through semi-permeable membrane.

_____________3. The pressure exerted by the surface of a liquid to become gas at specific temperature.

_____________4. Properties of solution that depends on the number of solute present rather than the nature of solute.

_____________5. Materials that allows small particles to pass through.

ASSIGNMENT

In your Journal, answer this question:

What are the other applications of colligative properties of solutions? Discuss briefly.

State references used.

Bring pins