Intermolecular Forces

Question 1

What types of molecules have electrons that ARE shared equally/the electrons are NOT moved in one particular direction (ex: CF4)

Answer 1

Non-polar molecules

Question 2

ALL hydrocarbons are what (ex: C3H3)?

Answer 2

Non-polar

Question 3

What types of molecules have electrons that are NOT shared equally/the electrons ARE moved in one specific direction (ex: CHF3)?

Answer 3

Polar molecules

Question 4

What do polar molecules tend to be?

Answer 4

Dipole

Question 5

What are forces between molecules that can determine the property of a substance called?

Answer 5

Intermolecular forces (IMF)

Question 6

Which type of IMF is being described?:
- Everything has _______
- is the WEAKEST type of IMF
- single atoms only have _______
- ex: Kr (Krypton)

Answer 6

London Dispersion

Question 7

Which type of IMF is being described?:
- occurs between POLAR molecules
- creates PERMANENT ______ (they will always stick together after initial attraction)
- has stronger IMF than London dispersion
- ex: 2 HBr molecules

Answer 7

Dipole-Dipole

Question 8

Which type of IMF is being described?:
- not really a traditional bond
- occurs between specific atoms (O-H, F-H, N-H)
- partial charges are more EXTREME than dipole-dipole
- stronger IMF than dipole-dipole
- ex: 2 H2O atoms

Answer 8

Hydrogen “bonding”

Question 9

Which type of IMF is being described?:
- half IONIC and half DIPOLE
- charges are FULL, not partial
- STRONGEST IMF
- ex: Na+ in H20

Answer 9

Ion-Dipole

Question 10

For IMF, larger charges equal what?

Answer 10

Stronger attraction

Question 11

For IMF, longer distance equals what?

Answer 11

Weaker attraction

Question 12

What is the energy needed to INCREASE the surface area (or break the “skin”) (ex: water bubbling over a cup)?

Answer 12

Surface tension

Question 13

What is the relationship between IMF and surface tension (effect of IMF)?

Answer 13

Higher IMF= Higher surface tension (b/c of intense attraction)

Question 14

What is the resistance of a liquid to flow (thick substance)?

Answer 14

Viscosity

Question 15

What is the relationship between IMF and viscosity (effect of IMF)?

Answer 15

Higher IMF= Higher viscosity (b/c they want to stick together)

Question 16

What is the ability of a liquid to move up a thin line AGAINST gravity?

Answer 16

Capillary action

Question 17

What are the attractions (IMF) WITHIN A substance (ex: mercury in a test tube)?

Answer 17

Cohesive forces

Question 18

Do cohesive forces have weak or strong adhesive forces?

Answer 18

Weak adhesive forces

Question 19

What are the attractions (IMF) BETWEEN TWO substances (ex: water in a test tube)?

Answer 19

Adhesive forces

Question 20

What are the determinants of IMF strength?

Answer 20

Molar mass and surface area

Question 21

What is the relationship between molar mass and boiling point?

Answer 21

Higher molar mass=Higher boiling point

Question 22

What is special about the aspect of surface area in IMF strength?

Answer 22

If the molar masses are equal, the one with a HIGHER surface area has HIGHER IMF

Question 23

What is the transition from a liquid to a gas (phase change) (ex: when a rain puddle disappears after a few days)?

Answer 23

Vaporization

Question 24

What is the transition from a gas to a liquid (phase change)?

Answer 24

Condensation

Question 25

What are the effects of vaporization?

Answer 25

1.) Temperature/Energy 2.) IMF 3.) Surface Area

Question 26

What is the relationship between temperature/energy with vaporization?

Answer 26

Higher vaporization=Higher temperature

Question 27

What is the relationship between IMF and vaporization?

Answer 27

Higher vaporization=Less strength of IMF (ex: it takes more energy to break apart stronger magnets than weak ones)

Question 28

What is the relationship between surface area and vaporization?

Answer 28

Higher vaporization=Higher surface area

Question 29

Is vaporization exothermic or endothermic?

Answer 29

ENDOthermic (+) (is TAKING energy)

Question 30

What is the first step of comparing molecules vapor pressure, boiling point, and IMF?

Answer 30

You can compare the TYPES/NUMBER of IMF the molecules have (the more IMFs they have, the HIGHER their boiling points are and the LOWER their vaporization and vapor pressure)

Question 31

What is the second step of comparing molecules vapor pressure, boiling point, and IMF?

Answer 31

You can compare how many H-BONDS they have (the more H-bonds they have, the HIGHER IMF they have, the HIGHER boiling points they have, and the LOWER their vaporization and vapor pressure are)

Question 32

What is the third step of comparing molecules vapor pressure, boiling point, and IMF?

Answer 32

You can compare the molecules' molar masses (the HIGHER the molar mass, the HIGHER the boiling point; the HIGHER the boiling point, the LOWER the vapor pressure and vaporization)

Question 33

What is the relationship between boiling point and vapor pressure?

Answer 33

Higher boiling point=Lower vapor pressure

Question 34

What is the relationship between boiling point and vaporization?

Answer 34

Higher boiling point=Lower vaporization

Question 35

What is the temperature at which a liquid's vapor pressure equals external pressure (atmospheric pressure)?

Answer 35

Boiling

Question 36

What is the boiling point when surrounding pressure equals 1 atm?

Answer 36

Normal boiling point

Question 37

What is the relationship between temperature and vapor pressure?

Answer 37

Higher temperature=Higher vapor pressure