Vapour Pressure

Question 1

Define vapour pressure

Answer 1

• Liquid evaporates - pressure exerted by vapour above the liquid
• More molecules escaping liquid = greater vapour pressure — more molecules have Ek great enough to escape

Question 2

When does vapour pressure reach equilibrium?

Answer 2

Number of vapour molecules re-joining liquid = number of molecules leaving to go into vapour phase (equilibrium reached)

Question 3

Effects of temperature on vapour pressure

Answer 3

Vapour pressure increases as temperature increases due to Ek increase

Question 4

Effects of surface area on vapour pressure

Answer 4

None

Question 5

Describe the effects of boiling

Answer 5

Liquid molecules leave for vapour phase
=> P(external) > P(cavity) - cavity collapses
=>P(external) < P(cavity) - cavity remains/expands and boils

Question 6

Effects of pressure difference on vapour pressure

Answer 6

Pressure difference increases, vapour pressure increases