Boiling Point, Freezing Point, Osmosis, and Solutes

exam 1, chem 116, WVU spring '26

Normal boiling point: definition

boiling point at 1 atm

Boiling point elevation: formula

ΔTb = (i) (Kb) (m)

i

van’t Hoff factor; number of dissolved particles per solute unit

Kb

boiling point elevation of the solvent

m

molality of the solution

Freezing point depression

ΔTf = (i) (Kf) (m)

Kf

freezing point depression of the solvent

Osmosis

net movement of a solvent through a semi-permeable membrane

Osmotic pressure: definition

pressure applied to stop the natural flow of the solvent

As evaporation occurs, osmotic pressure will ___

increase, since the solution has a higher molarity

Osmotic pressure: formula

P = i M R T

M

molarity

R

.08206 (L ATM) / (mol K)

Suspensions

particle size > 1,000 nm

Colloid

particle size between 1 - 1,000 nm

Solution

<1 nm

A true solution ___

doesn’t scatter light

Pure solvents always have the highest ___

freezing point

Pure solvents always have the lowest ___

boiling point