Lecture 28 Flashcards
(21 cards)
What happens to KE when temperature increases
The KE increases, particles move faster and overcome attractions more easily
What happens to KE when temperature decreases
KE decreases, particles move slowly and attractions can pull them together more easily
What is the process of solid -> gas called
Sublimation
What is the process of gas -> solid called
Deposition
What is the process of liquid -> gas called
Vaporization
What is the process of gas -> liquid called
Condensation
What changes are exothermic (release heat)
Condensation
Freezing
Deposition
What processes are endothermic (absorb heat)
Sublimation
Melting
Vaporization
What is distrupted during a phase change
Non-bonding forces
Why is Hfus < Hvap
It takes less energy to reduce intermolecular forces enough to move particles out of their fixed positions than to separate them completely
What happens when frost forms
Deposition, exothermic
What happens in the equilibrium process
The rate of vaporization and condensation are equal
Same number of molecules entering & leaving the liquid (pressure remains constant)
Why is equilibrium dynamic
Because there is still movement in the molecules
What effect does temperature have on vapour pressure
It changes the fraction of molecules moving fast enough to escape into the the gas phase and the ones not moving fast enough to recondense into a liquid
What happens when the rate of vaporization matches the rate of condensation
A dynamic equilibrium is (1=g) is established, as long as there is liquid present the pressure reaches a constant value called vapour pressure
The higher the temperature the ————- the vapour pressure
Higher
What is the vapour pressure of strong/weak intermolecular forces
Strong IMF: low vapour pressure (ex. H2O)
Weak IMF: high vapour pressure (ex. Diethyl ether)
What is the normal boiling point
The temperature at which the vapour pressure is 1 atm
Define boiling point
Temperature at which the vapour pressure in the liquid equals the external pressure, which is usually the atmospheric pressure
Explain volatile substances
- high vapour pressure
- low bp
- weak IMF
Explain non-volatile substances
- low vapour pressure
- high bp
- strong IMF
