Lecture 3 Solutions and Colligative Properties Flashcards

Flashcards on Solutions and Colligative Properties

Henry's Constant

A constant that relates the solubility of a gas in a liquid to the pressure of the gas above the liquid.

Molality (m)

amount of solute (in mol) / mass of solvent (in kg)

Molarity (M)

amount of solute (in mol) / volume of solution (in L)

Mole Fraction (X)

amount solute (in mol) / total amount of solute and solvent (in mol)

Parts per Million (ppm)

(mass solute / mass solution) x 10^6

Parts per Billion (ppb)

(mass solute / mass solution) x 10^9

Colligative Properties

Physical properties of a solution that depend only on the number of solute particles dissolved in the solution, not the identity of the particles.

Strong Electrolyte

A solute that completely dissociates into ions when dissolved in water, resulting in a large number of solute particles.

Weak Electrolyte

A solute that partially dissociates into ions when dissolved in water, resulting in a smaller number of solute particles.

Nonelectrolyte

A solute that does not dissociate into ions when dissolved in water, resulting in the same number of solute particles as the number of molecules dissolved.

Vapor Pressure

The pressure of a vapor/gas above its liquid when the two are in equilibrium.

Volatile

Liquids that exhibit high vapor pressures.

Raoult's Law (Nonvolatile Solute)

Psolution = solvent P° solvent where Psolution = vapor pressure of the solution, P° solvent = vapor pressure of the pure solvent, and solvent = mole fraction of solvent.

Raoult's Law (Volatile Solute)

Psolution = A P° A + B P° B where A and B = mole fractions of A and B in solution and P° A and P° B = vapor pressures of pure A and pure B.

Ideal Solution

A solution in which the solvent-solute interactions are similar in magnitude to both the solute-solute interactions and the solvent-solvent interactions; obeys Raoult's law at all concentrations.

Freezing Point Depression

The decrease in the freezing point of a solvent when a solute is dissolved in it.

Boiling Point Elevation

The increase in the boiling point of a solvent when a solute is dissolved in it.

Osmosis

The flow of solvent across a semipermeable membrane from a solution of low concentration into a solution of high concentration.

Semipermeable Membrane

A membrane that allows the flow of solvent particles but not the flow of solute particles.

Osmotic Pressure (P)

The amount of pressure needed to keep osmotic flow from taking place; P = MRT where M = molarity of the solution, R = gas constant, and T = temperature.