Unit 1 - Matter and Energy - Vapor Pressure

Question 1

Definition of Vapor Pressure (4)

Answer 1

1. Pressure created by the gas
2. Forms above a liquid in a closed container
3. Exert a pressure on the container walls
4. A measure of how motivated it is to turn into a gas

More motivated molecules to evaporate = High VP = High volatility

Question 2

What is the relationship between temperature and vapor pressure? (3)

Answer 2

1. Higher Temperature = More KE
2. More KE = More Evaporation
3. More Gas Molecules = More Vapor Pressure

(When molecules move faster, they are more likely to break free from the liquid phase)

Question 3

Relationship between BP and VP

Answer 3

Higher VP = Lower BP

Boiling: VP = AP

Question 4

Votality

Answer 4

How easily a liquid can form into a gas

Question 5

What are two factors that affect the volatility of a substance?

Answer 5

1. Strength of Intermolecular Forces
2. Viscosity

Think of honey (high viscosity, low volatility) vs. gasoline (low viscosity, high volatility). They’re different ends of the spectrum.

Question 6

Relationship between Vapor Pressure and Strength of Intermolecular Forces

Answer 6

High VP: Weak forces = More evaporation
Low VP: Strong forces = Less Evaporation

It takes less energy to break weak forces and change the phase of the substance.

Question 7

Relationship of Delta T and Vapor Pressure

Answer 7

Higher Delta T, Higher VP

Question 8

Relationship of Delta T and Boiling Point

Answer 8

Higher Delta T, Lower Boiling Point