colligative properties of solutions

colligative properties

• Properties that depend on the concentration of solute particles but not on their identity

the boliing point of a solution differ from those of the pure solvent

nonvolatile substance

• substance that has little tendency to become a gas under existing conditions

nonelectrolyte solutions of the same molality have the same conecntration of partilces.

freezing-point depression

• the freezing-point depressino of a 1 m solution of any nonelectrolyte solute in water is found by experiment to be 1.86 degrees Celsius lower than the freezing point of water.

molal freezing-point constant

• the freezing point depresino of the solvent in a 1-molal solutino of a nonvolatile, noneletrolyte solute

freezing point depression

• the difference between the freezing points of the pure solvent and a solution of a nonelectrolyte in that solvent, and it is directly proportional to the molal concentration of the solution

Ksub f is expressed as degrees Celsius/m

each solvent has its own characteristic molal freezing point constant

boiling point elevation

• the boiling point of a liquid is the temperature at which the vapor pressure of the liquid is equal to the prevailing atmospheric pressure
• a change in the vapor pressure of the liquid will cause a corresponding change in the boiling point

molal boiling point constant

• the boiling point elevation of the solvent in a 1-molal solution of a nonvolatile, nonelectrolyte solute.
• the boiling point elevation of a 1-molal solution of any nonelectrolyte solute in water has been found by experiment to be 0.51 degrees C

boiling point elevation

• the difference between the boiling points of the pure solvent and a noneletrolyte solution of that solvent, and is directly proportional to the molal concentration of the solution
• change in temperature = (constant of temperature) (m)

osmotic pressure

• the external pressure that must be applied to stop osmosis

osmosis

• the movement of solvent through a semipremeable membrane from the side of lower solute concentration to the side of higher concentration

semipermeable membrane

• membrane that allows the passage of some particles while blocking the passage of others