Chemistry Test #10

Colligative Properties

A property that depends only on the number of solute particles

Four Colligative Properties

Vapor Pressure Depression

Freezing Point Depression

Boiling Point Depression

Osmosis

Freezing Point Depression

When substance freezes, particles arrange into orderly arrangement to form solid

Freezing Point lowers when solute is added, the solvent particles are attracted to the solute and the solid arrangement becomes disarray

Molal Freezing Point constant

K_f H20= 1.86 C/m

Change in Freezing Point Formula

T_f = iK_fm

Electrolytes

Substances that conduct electric currents as the result of a dissociation into positive and negative ions

Nonelectrolytes

molecular compounds (non conductors)

Which Solution has lower Freezing Point: 3 mol N₂O₅ or 2 mol Ca(NO₃)₂

Ca(NO₃)₂ because it has more particles

Vapor Pressure

The pressure of vapor above a liquid

Decreases when solute particles added because solvent attracted to solute. The solute leaves as a vapor

Which has higher vapor pressure: 1 mol NH₄NO₃ or 1 mol AlBr₃

1 mol NH₄NO₃ because it has weaker bond.

Boiling Point Elevation

Boiling point increases when a solute is added because the solvent particles are attracted to the solute, so they do not leave and become gas.

Change in Boiling Point Formula

T_b= iK_bm

K_b = 0.512 C/m

Osmosis- Osmotic Pressure

Osmosis is the net movement of solvent toward the solution with higher solute cone

Semipermeable

Materials that only allow some molecules to pass through

Molarity

Ratio of the moles of solute over liter of solution

Molality

Ratio of moles of solute over kilograms of solvent