chapter 11

Question 1

what is the order of the 5 imfs in order of strongest to weakest?

Answer 1

1. ion-ion
2. ion-dipole
3. dipole-dipole
4. dipole-induced dipole
5. induced dipole-induced dipole

Question 2

how do you compare the strenghs of 2 ion ion forces?

Answer 2

-boiling point (Higher bp = stronger force.)
- charge of ions

Question 3

how do you compare strenghs for ion dipole forces?

Answer 3

• higher charge = higher attraction
• bigger dipole moment = stronger attraction
• smaller radius = stronger ion
• biggest ΔH (absolute value) = stronger bond

Question 4

what is an example of ion dipole forces?

Answer 4

dissolving nacl in water. By trading the only ion ion force for 6 forces. That’s why nacl dissolves well.

Question 5

what does the dipole dipole force influence?

Answer 5

the evaporation of a liquid and the condensation of gas.

Question 6

how to compare strenghs of dipole dipole forces?

Answer 6

• boiling point: higher bp = stronger force
• ΔHvap: bigger = more polar = stronger force

Question 7

if oxygen is a central atom, is the molecule polar?

Answer 7

yes, because it creates a bent geometry.

Question 8

why does water have the highest boiling point?

Answer 8

since water has many opportunities for Hbonding (2H and 2 lone pairs), thoses bonds are very strong and hard to destroy.

Question 9

why does ice float on water?

Answer 9

in the liquid state, molecules of water move around. Though, when it freezes and becomes ice, the water molecules all arrange perfectly in a way that leaves a lot of empty space, so it’s less dense.

Question 10

what is the name of the action of inducing a dipole?

Answer 10

polarization

Question 11

how does the molar mass affect the solubility of a dipole-ID force?

Answer 11

the bigger the molar mass, the larger the electron cloud (so the higher the polarizability, the bigger the dipole moment, the higher the solubility.

Question 12

how to compare strengths of dipole-ID forces?

Answer 12

• using molar mass or number of electrons.

Question 13

what is the only possible force in two nonpolar molecules?

Answer 13

ID-ID

Question 14

how to compare strengths of ID-ID?

Answer 14

• size (bigger molecule = bigger polarizability = stronger)
• ΔHvap: higher = stronger
• bp : higher = stronger

Question 15

what is ΔHvap?

Answer 15

the energy needed to vaporize a molecule (enthalpy of vaporization)

Question 16

what is the relationship between ΔHvap and bp for nonpolar liquids?

Answer 16

• bp/ΔHvap increases as the size increases

Question 17

what are the exceptions to the relationship between ΔHvap and bp?

Answer 17

when there is a Hbond

Question 18

what is the vapor pressure?

Answer 18

• the pressure exherted by the vapor in equilibrium with the liquid phase.
• a measure of the tendency of liquid molecules to escape from liquid phase and go into gas phase at given T.

Question 19

what is the relationship between Pvap and bp?

Answer 19

higher bp = more polar = stronger = less volatile

Question 20

what is viscosity?

Answer 20

the resistance of liquids to flow.

Question 21

what is the relationship between size and viscosity?

Answer 21

bigger = more tangling = difficulty to flow = more viscous

Question 22

what is the relationship between viscosity and imfs?

Answer 22

stronger bond = harder to flow = more viscous

Question 23

what is surface tension?

Answer 23

the net inward force created at the top of a liquid which creates a tension at the surface.

Question 24

how do you break surface tension?

Answer 24

• using mechanical energy
• adding something on top (ex soap)

Question 25

what causes capillary action and meniscus?

Answer 25

IMFs

Question 26

how do you explain a downward meniscus?

Answer 26

the adhesive forces are not as strong as the cohesive forces, so the meniscus is downward.

Question 27

what are adhesive forces?

Answer 27

forces between the liquid and the side of the container in which it is in

Question 28

what are cohesive forces?

Answer 28

the forces between the molecules of liquid themselves.

Question 29

how do you explain an upward meniscus?

Answer 29

the adhesive forces are stronger than the cohesive forces, so the meniscus goes up the side of the container.