chapter 13

Question 1

what is molality?

Answer 1

mol of solute / kg of solvent

Question 2

what is mole fraction?

Answer 2

moles of asked compound / total moles of solution

Question 3

what is molarity?

Answer 3

mol of solute / L of solution

Question 4

what is weight percent?

Answer 4

(mass asked compound / total mass) x100

Question 5

is hydration endo or exo?

Answer 5

exo (ions become surrounded by water)

Question 6

is the seperation of the ions (lattice) endo or exo?

Answer 6

endo- requires energy

Question 7

what makes a favorable process for solubility?

Answer 7

when solute-solvent and solute-solute forces are similar.

Question 8

what is ΔH solution?

Answer 8

ΔH solvation(hydration) - ΔHlattice

Question 9

what is henrys law and what does it give us?

Answer 9

Sg = Kh x Pg (solubility of the gas)

Question 10

what is the effect of pressure on solubility?

Answer 10

more pressure = more gas entering liquid = more soluble

Question 11

what is the effect of size and polarizability on solubility?

Answer 11

tow molecules of same size will dissolve better
more polar = more soluble in polar compounds

Question 12

what is the effect of temperature on solubility?

Answer 12

at a lower temperature, more gas is dissolved, because by creating forces with a gas, there is a drop in potential energy, so it needs to be released.

Question 13

what are the colligative properties?

Answer 13

-properties that depend on the relative nb of solute and solvent in a solution, not on their identity.
-Pvap, boiling point, freezing point, osmotic pressure

Question 14

what is the formula for Pvap?

Answer 14

Pa = Xa x Pa(pure)

Question 15

how is the vapor pressure affected?

Answer 15

the more you dissolve, the less vapor is generated, the lower Pvap is

Question 16

is the vapor pressure of a pure gas bigger than this gas in a solution?

Answer 16

yes

Question 17

how is the boiling point affected?

Answer 17

• lower Pvap = higher b.p.
• the more you dissolve, the higher the b.p.

Question 18

what is the formula to find out the difference in b.p.?

Answer 18

ΔTb.p. = Kb.p. x m x i

Question 19

how is the freezing point affected?

Answer 19

the more gas you dissolve, the lower the f.p.

Question 20

what is the formula for f.p.?

Answer 20

ΔTf.p. = Kf.p. x m x i

Question 21

what does i represent?

Answer 21

van’t hoff factor: depends on number of particles (when it’s a salt that breaks into ions, see how many particles there are)

Question 22

what is an ion-pair?

Answer 22

when there are big concentration, ion pairs create between the dissolved salt, making the van’t hoff factor smaller than expected. Bigger charge = more ion pairs

Question 23

what is osmosis?

Answer 23

-we want concentration inside to be equal to concentration outside
- solvent particles move through the semi permeable membrane (but NOT solute/ions)

Question 24

what is the formula for osmotic pressure?

Answer 24

π = cRT x i = nRT/V x i

Question 25

what is a colloid?

Answer 25

particles that are suspended but not dissolved
ex: soap