Unit 11- Liquids and Solids

Question 1

intermolec forces

Answer 1

attraction that hold molecs together in the liquid and solid states

Question 2

gas

Answer 2

• assumes vol/shape of cotainer
• low density
• easily compressed
• kinetic energy &laquo_space;energy of attraction

Question 3

liquid

Answer 3

• def vol, assume shape of container
• high density
• nearly incompressible
• kinetic energy = energy of attraction

Question 4

solid

Answer 4

• def vol and shape
• high density
• nearly incompressible
• kinetic energy&raquo_space; energy of attraction

Question 5

evaporation

Answer 5

process by which molecs escape from the liquid to the gas phase

Question 6

condensation

Answer 6

process by which molecs go from the gas phase to the liquid phase

Question 7

Maxwell-Boltzmann Distribution

Answer 7

as temp inc, # of molecs that can evap inc

Question 8

gas pressure above liquids

Answer 8

• pressure in gas phase inc as molec evap from liquid
• pressure becomes const when evap = condensation

Question 9

Dynamic equilibrium

Answer 9

state in which the 2 opposing changes occur at equal rates, so net change is apparent
- indicated by double arrow

Question 10

vapor pressure

Answer 10

partial pressure of the gas when the rate of evapo = rate of condensation
- as temp inc, the vapor pressure of a liquid incs
- the stronger the intermolec forces, the lower the vapor pressure of the liquid at any temp

Question 11

boiling point

Answer 11

temp the vapor pressure is = to external pressure

Question 12

normal boiling point

Answer 12

temp at which vapor pressure = to 1 atm

Question 13

enthalpy of vap

Answer 13

enthapy change that accompanies conversion of 1 mol of sub from a liquid to a gas at const temp (L —> g)

Question 14

vap and intermolec forces

Answer 14

as strength of forces inc, VP dec, b.p inc, and deltaHvap inc

Question 15

liquid-solid equilibrium

Answer 15

changes of a sub from liquid to solid (freezing) and from solid to liquid (melting or fusion)
- involve dynamic equilib

Question 16

melting point

Answer 16

temp solid and liquid phases are in equilib when the pressure is 1 atm (pressure has little effect on melting point)

Question 17

enthalpy of fusion

Answer 17

enthalpy change that accompanies the change of 1 mol of solid into liquid at const temp

Question 18

heating curves

Answer 18

graph of temp of sample vs heat added
- first angle is solid
- second angle is liquid
- third angle is gas

Question 19

sublimation

Answer 19

solid to the gas phase

Question 20

deposition

Answer 20

gas to solid phase

Question 21

enthalpy of sublimation

Answer 21

enthalpy change fro the conversion of 1 mol of sub from solid to gas
deltaHsub = deltaHfus + deltaHvap

Question 22

phase diagrams

Answer 22

graph of pressure vs temp that shows the region of stability for each phase
- first inc= s-g equilib line
- second inc= l-g equilib line
- vertical line= s-l quilib line

Question 23

melting pt and pressure

Answer 23

• if solid is more dense than liquid (common), melting pt INCS w/ INC pressure
• If liquid more dense (H2O), melting point DECS w/ INC pressure

Question 24

electrostatic forces

Answer 24

accounts for all types of intermolec forces
- dipole-dipole attractions
- London dispersion
- Hydrogen bonding

*London < Dipole < hydro

Question 25

dipole-dipole attraction

Answer 25

results from electronic forces between molec dipoles. Must be POLAR
* polarity inc, dipole inc

Question 26

London dispersion forces