Vaporization

Vaporization

Evaporation in an open container. Condensation rate will probably never be as high as evaporation rate.

Vaporization

VaporizationEvaporation in a closed container. Condensation rate will eventually equal evaporation rate.

Vaporization

What factors affect the rate of evaporation?

How Temperature Affects Evaporation Rate

What factors affect the rate of evaporation?

Temperature

Surface area

Strength of intermolecular attractive forces

What factors affect equilibrium vapor pressure?

What factors affect equilibrium vapor pressure?

Temperature

Strength of intermolecular attractive forces

Boiling

Boiling

An Exponential Equation for Pressure

• P = β exp(-ΔHvap /RT)

• ln P = ln β + ln exp(-ΔHvap / RT)

• ln P = ln β - ΔHvap / RT

• ln P = ln β - (ΔHvap / R) (1 / T)

• Y = b + mX

• Plot ln P against 1 / T. Slope = -ΔHvap/R

• ΔHvap = -R . Slope where R = 8.314 J / K mol

The 2-Point Clausius-Clapeyron Equation

• ln P = ln β - (ΔHvap / R) (1 / T)

• ln P2 = ln β - (ΔHvap / R) ( 1 / T2)

• Ln P1 = ln β - (ΔHvap / R) (1 / T1)

• ln P2 - ln P1 = (ΔHvap / R) (1 / T1 - 1 / T2)

• Ln (P2 / P1) = (ΔHvap / R) (1 / T1 - 1 / T2)