Unit 11: Solutions

Solution

a homogeneous mixture of ions or molecules

Solute

the dissolved substance

Solvent

the dissolving medium

"Like dissolve like" principle

two substances with intermolecular forces of similar type and magnitude are likely to be soluble

Solubility

the amount of a substance that dissolves in a solvent

Saturated solution

one holding as much solute as is allowed at a stated temperature

Molarity

of a solute is the amount of moles that dissolves in a volume of the solution at a given temperature

Molality

the moles of solute per kilogram of solvent

Nonpolar solvents dissolve _ solutes

Nonpolar solvents dissolve NONPOLAR solutes

Polar solvents dissolve _ solutes

Polar solvents dissolve POLAR solutes

Similar intermolecular forces = _

Solution

Different intermolecular forces = _

No Solution

Henrys Law

solubility of a gas in a liquid is proportional to partial pressure of the gas in contact with the liquid

∆H ion ion

Energies holding solute ions in crystal lattice

∆H dipole dipole

Energies holding solvent molecules together

∆H ion dipole

attractions between solute ions and solvent molecules

Lattice Energy [U]

The energy released when one mole of the ionic compound forms form its free ions in the gas phase

Colligative Properties

those properties that depend on solute concentration

4 Colligative properties of solutions

1. vapor pressure reduction 2. freezing point depression 3. boiling point elevation 4. osmosis

Raoults Law

vapor pressure of a solution containing a solute is proportional to the mole fraction of the solvent

Boiling Point Elevation

Because vapor pressure is reduced in the presence of a nonvolatile solute a greater temperature must be reached to achieve boiling

Osmosis

movement of solvent through semi-permeable membrane from region of low solute concentration to region of higher solute concentration

Osmotic Pressure

pressure required to halt flow of solvent through membrane due to osmosis