12E - Colligative Properties

Question 1

Def: What is a colligative properties?

Answer 1

Properties that depend on the relative amounts of solute and solvent. Independt of chemical idenity of solute.

Question 2

Recall: What are electrolytes vs N-E?

Answer 2

Seperate into ions when dissolved or does not (can still seperate).

Question 3

Def: What are extensive and intensive properties?

Answer 3

Depend on quanitiy of matter (moles, mass), like volume, mass…
Independent of quantitty of matter, like desnity, temp.

Question 4

Def: What is raoult’s law? What does it apply to.

Answer 4

P-solvent = x-solvent*P-pure
P-pure is pressure of pure solvent.

Applies to nonvolatile splutes whose Vap-pressure is negligable and ideal soln.

Question 5

Def: What is raoult’s law concering pressure of solute?

Answer 5

delta-P = x-solute*P-solventnot

Question 6

Def: What is a binary liquid?

Answer 6

When mixed are nearly indentical as they have similar moleculat structures.

Question 7

Def: What is the total pressure vapour pressure formula for two volatile liquids.

Answer 7

Sum of both vapor pressures.
Ptotal = X-AP-A + X-BT-B
A and b are volatile liquids

Question 8

Theory: When two volatile components are mixed, what happens to each of their vapor pressures?

Answer 8

Both lower, as mole fraction for both goes down.

Question 9

Theory: what happens to vapour pressure is solute is added to a solution.

Answer 9

Mol fraction goes down, vapour pressue goes down

Question 10

Def: What is bp elevation? What is the formula?

Answer 10

Increased bp caused by decreased Vapor pressure caused by adding solute.
delta-T-b = Tb - T-bnot = ik_bb
i is van hoff factor, can be ignored for molecular compounds
K-b is bp elevation constant
b is molaity

Question 11

Theory: What is the bp elevation constant a property of?

Answer 11

Solvent, not solute

Question 12

Theory: bp of soln is always _ than that of the pure solvent.

Answer 12

greater than

Question 13

Def: What is the formula for change in boiling point (or bp-elevation) using the original bp?

Answer 13

delta-T-b = k-b * b

Question 14

Def: What is the vant hoff factor?

Answer 14

Bcs strong electrolytes ionize in soln, i is the apparent number of ions per formula unit.
If non-ionising, it’s 1.
i = number of ions on dissocaition
- Usually lower

Question 15

Def: What is total molal concentration?

Answer 15

Differnce between freezinf point of pure solvent and freezing point of soln.

Question 16

Def: What is freezing-point-depression?

Answer 16

Lowering freezing points.
delta-T-f = T-fnot - Tf = ik-fb
Note, this is initial minus final.

Question 17

Theory: If multiple solutes have equal molalities, how can the lowest freezing point be found?

Answer 17

Look for highest hoff factor.

Question 18

Def: What is osmosis? what wat will solvent flow?

Answer 18

Movement of solvent particles from higher to lower region of concentration through membrane. Flow away from more dilute soln to a more concentrated one.

Question 19

Def: What is osmotic pressure?

Answer 19

Pressure that must be applied to prevent net flow of solvent due to osmosis.
cpi = iMRT

Question 20

Def: What is a strong electrolyte? How can hoff factor determine one?

Answer 20

Disassociated completely into ions. Hoff factor takes into account the dissassoscation of a strong electrolyte to predict effect on soln.
i = measured value for electrolyte soln / expected value
value meaning number of ions produced

Question 21

Def: What is reverse osmosis?

Answer 21

Pressure applied to diluted side pushes water through membrane.
P > cpi