Solutions

Question 1

Components

Answer 1

minimum number of independent species necessary to define the composition of all phases in a system

Question 2

Phase diagram

Answer 2

Plot of pressure vs temperature

Question 3

Phase boundary

Answer 3

Continuous line representing values at which equilibrium exists between 2 phases

Question 4

Triple point

Answer 4

Point at which 3 phases coexist at equilibrium

Question 5

What is different about water phase diagram?

Answer 5

Solid/Liquid line leans towards the y-axis.

Question 6

Why is the water phase diagram different?

Answer 6

The solid/liquid line leans towards the y-axis due to being less dense in the solid phase than liquid phase. This is due to H bonding and oxygen repelling other oxygens

Question 7

Degrees of Freedom

Answer 7

Number of factors which can be varied independently without altering the number of phases

Question 8

Gibbs Phase Rule in condensed systems

Answer 8

P+F = C+1

Question 9

Gibbs Phase Rule

Answer 9

P+F = C+2

Question 10

Colligative Properties

Answer 10

4 physical properties affected in the same way by solutes, regardless of solute identity

Question 11

What do Colligative Properties depend on?

Answer 11

Properties of solvent, concentration of dissolved substance and number of particles of dissolved substance in the solution

Question 12

How are the colligative properties related?

Answer 12

Thermodynamically

Question 13

What are the 4 main Colligative Properties?

Answer 13

Vapour Pressure lowering, Freezing point depression, boiling point elevation and osmotic pressure

Question 14

Osmosis

Answer 14

The tendency of solvent molecules to pass through a membrane from a more dilute to a more concentrated solution.

Question 15

Osmotic pressure

Answer 15

If a solution is separated from its solvent by a membrane then the excess pressure which has to be applied to prevent the flow of the solvent is the osmotic pressure

Question 16

Osmotic pressure equation

Answer 16

Π = mRT

Question 17

Semi-permeable membrane

Answer 17

Chemical potential of a solvent in solution is less than its chemical potential in a pure solvent. Solvent passes spontaneously into the solution to equalise the chemical potential on either side of the membrane

Question 18

Reverse Osmosis

Answer 18

A pressure greater than the osmotic pressure is applied to the solution and forces the solvent through the membrane

Question 19

Hydrostatic pressure

Answer 19

Pressure exerted by a column of aqueous solution

Question 20

Iso-osmotic

Answer 20

2 solutions have the same osmotic pressure

Question 21

Isotonic

Answer 21

2 solutions have the same solute concentration

Question 22

If osmotic pressure is hypotonic, what happens to cells?

Answer 22

They swell

Question 23

If osmotic pressure is hypertonic, what happens to cells?

Answer 23

They shrink

Question 24

What is the osmotic pressure of blood?

Answer 24

291 m osmol dm-3

Question 25

Osmolality

Answer 25

The mass of solute which when dissolved in 1kg of water will exert an osmotic pressure equal to that exerted by 1 mol of an ideal and unionised substance dissolved in 1kg of water

Question 26

Osmol

Answer 26

A mole of a substance that is non-dissociable in a solution

Question 27

Freezing point depression of blood

Answer 27

ΔTf = 0.52°C

Question 28

Freezing point depression

Answer 28

Freezing point depression is the lowering of the freezing point of a solvent by adding a non-volatile solute

Question 29

Equation for freezing point depression

Answer 29

ΔTf = Kf x m

Question 30

Osmotic pressure equation using ΔTf

Answer 30

Π = ΔTf/Kf x RT

Question 31

What is W = 0.52-a / b used for?

Answer 31

When it is not possible to adjust the concentration of a drug to make it more isotonic with blood, an adjusting substance can be added. W = weight of adjusting substance per 100cm3 a= ΔTf of drug solution b = ΔTf produced by 1%w/v of adjusting substance

Question 32

Solubility of gas in a liquid

Answer 32

The concentration of the dissolved gas when it is at equilibrium with some of the pure gas above the solution

Question 33

Henry's Law

Answer 33

The vapour pressure exerted by a gas dissolved in a solvent at constant temperature is proportional to the mole fraction of the gas

Question 34

Henry's Law equation

Answer 34

pB = kH + xB xB = mole fraction of the gas pB = vapour pressure of the gas kH = Henry's Law constant

Question 35

What happens to gas solubility as temperature increases?

Answer 35

Gas solubility decreases due to the greater tendency of gas to expand

Question 36

Salting out

Answer 36

Liberation of gas from a solution by the addition of NaCl or sucrose. The added solute attracts water molecules, reducing the density of the aqueous environment adjacent to the gas molecules

Question 37

Degrees of Freedom in an immiscible solution

Answer 37

2 degrees of freedom

Question 38

Degrees of Freedom in a miscible solution

Answer 38

3 degrees of freedom

Question 39

Upper Critical Solution temperature

Answer 39

Highest temperature at which phase seperation occurs. This is due to thermal motion overcoming potential energy advantage of one type of molecule being close together

Question 40

Lower critical solution temperature

Answer 40

Temperature at which they mix in all proportions and above which they form 2 products. More miscible at low temperatures as a weak complex is formed

Question 41

Phase diagram point B

Answer 41

The eutectic point - the lowest temperature at which liquid solution can exist

Question 42

Raoult's Law

Answer 42

Applies to solvent in solution

Question 43

Raoult's Law equation

Answer 43

pA = p°A xA p°A is the vapour pressure of pure solvent pA is the vapour pressure of solvent in solution xA is the mole fraction of the solvent

Question 44

Mole fraction in Henry's and Raoult's law

Answer 44

xB = 1 - xA

Question 45

What solutions obey Raoult's law?

Answer 45

Ideal solutions

Question 46

How are non-ideal solutions formed?

Answer 46

Formed in the process of mixing of components and is accompanied by absorption of heat

Question 47

Theory of colloid stability

Answer 47

DLVO

Question 48

Total Vapour Pressure

Answer 48

pTotal = pA + pB

Question 49

Total potential energy using DLVO theory

Answer 49

vTotal = vA (attractive potential energy) + vR (Electrostatic repulsive energy)

Question 50

Low electrolyte concentration on DLVO plot

Answer 50

High primary maximum and no secondary minimum

Question 51

High electrolyte concentration on DLVO plot

Answer 51

No primary maximum or secondary minimum