Colligative properties

Question 1

Characteristics of osmotic pressure

Answer 1

• directly oppose osmosis (flow thru semiperm membrane)
• incr with temp (head speeds up motion of molecules in solution) > greater pressure
• not affected by chemical identiy of solute
• magnitude determined by number of particles dissolved

Question 2

Colligative properties depend on what:

Answer 2

number of solute molecules to number of solvent molecules

Question 3

Solute dissolvation and vapor pressure:

Answer 3

• solvent adheres to solute > less likely to evaporate, lowering vapor pressure
• dissolved solute near surface, physically prevent evaporation > reduce vapor pressure

Question 4

Formula for BP/FP change:

Answer 4

Change in temp = iKm

• i ion factor
• k constant for boil/freeze at certain temp
• m molality of solvent

Question 5

Equation for vapor pressure

Answer 5

vapor pressure= mol fraction (solvent) x vapor pressure (pure solvent)

Question 6

What is the relationship between vapor pressure and boiling point?

Answer 6

• adding solute reduces vapor pressure which increases Temp required to achieve boiling point

Question 7

what is boiling point definition

Answer 7

• vapor pressure equilibrium with atmospheric pressure

- thus at reduced atmospheric pressure, boiling point is lower

Question 8

what are the four colligative properties?

Answer 8

• osmostic and vapor pressure

- boiling and freezing poing