C3: Colligative Properties

Question 1

what does a colligative property depend on?
- what is it independent of?
- the # of particles depend on what?

Answer 1

• the # of solute particles in solution
• the identity of the particle
• iC, where:
  i= vant hoff factor (how many ions a solute can generate)
  C= concentration

Question 2

what is a volatile liquid?

Answer 2

a liquid with a high vapor pressure

Question 3

1cm^3= ____ mL

Answer 3

1

Question 4

1L= ____ mL

Answer 4

1000

Question 5

what is the formula for molality?

Answer 5

m= moles of solute/ kg of solvent

Question 6

what is the formula for Molarity?

Answer 6

M= moles of solute/ L of solution

Question 7

what is the formula for finding the mole fraction of a given substance (S)?

Answer 7

mole fraction of S = # of moles of substance S/ total # of moles in solution

Question 8

what kind of molecules have an i that is greater than 1?

Answer 8

• molecules that dissociate in solution
• with ionic bonds (salts/ electrolytes)
• strong acids/ bases

Question 9

what kind of molecules have an i that is equal to 1?

Answer 9

• molecules that dont dissociate in solution
• with covalent bonds (includes sugars)
• weak acids/bases
• organic compounds

Question 10

what is vapor pressure?
- VP will not change if you remove the ____ because it is only exerted by the ____, not the ____

Answer 10

pressure exerted by the gas phase above a liquid (due to vaporization)
- lid; vapor; atmosphere

Question 11

what do solutes do to vapor pressure? what is this called?

Answer 11

prevent vaporization, decreases and causes vapor pressure depression

Question 12

vapor pressure and ____ are inversely related

Answer 12

boiling point

Question 13

what is freezing point?
- what is the formula for it?

Answer 13

temperature at which freezing occurs
- change in Tf= (i)(m)(kf), where:
i= vant hoff
m= molality
kf= solvent specific constant

Question 14

what do solutes do to freezing point? what is this called?

Answer 14

prevent formation of solid solvent lattice required for solidification, decreases and causes freezing point depression

Question 15

what is the formula for freezing point depression?

Answer 15

change in Tf = -kf * i * m

Question 16

largest ____ gives greatest freezing point depression

Answer 16

i

Question 17

what is boiling point?
- this happens when ____ = ____
- what is the formula?

Answer 17

temperature at which boiling/ vaporization occurs
- vapor pressure= atmospheric pressure (numerically)
- same as FP except BP

Question 18

what do solutes do to boiling point? what is this called?

Answer 18

prevent vaporization, increases and causes boiling point elevation

Question 19

what is the formula for boiling point elevation?

Answer 19

change in Tb = kb * i * m
where:
kb: solvents boiling point elevation constant
m: molal concentration of the solution

Question 20

how much does 1L of water weigh in kg?

Answer 20

1kg

Question 21

what is osmosis?

Answer 21

the movement of water across a semipermeable membrane from a region of low solute concentration to a region of higher solute concentration in an effort to dilute the higher concentration solution

Question 22

what is osmotic pressure?
- what is the formula?

Answer 22

the external pressure required to stop osmosis between 2 solutions
- pi= (M)(i)(R)(T), where:
M= molarity
R= gas law constant (0.1 L atm/mol K)

Question 23

what do solutes do to osmotic pressure? what is this called?

Answer 23

increase force of osmosis, increases and causes osmotic pressure elevation