Solutions

Question 1

What is:

Brass?

Answer 1

A mixture of copper and zinc

Question 2

What is:

German silver?

Answer 2

A mixture of copper, zinc and nickel

Question 3

What is:

Bronze?

Answer 3

A mixture of copper and tin

Question 4

Fill in:

1ppm of flouride in water —-

Answer 4

—— prevents tooth decay

Question 5

Fill in:

1.5 ppm of flouride in water—–

Answer 5

——- mottles teeth

Question 6

Fill in:

Any concentration of flouride in water above that—–

Answer 6

—— is commonly used as rat poison

Question 7

Fill in:

A solution consists of——-

Answer 7

———- a solute and a solvent

Solute (present in lesser amounts)
Solvent (present in larger amounts)

Question 8

What is:

A binary solution?

Answer 8

A binary solution contains only 2 components

Question 9

List:

Types of binary solutions:

Answer 9

• Gaseous solutions
• Liquid solutions
• Solid solutions

Question 10

What is:

Mass percentage?

Answer 10

(mass of a substance/ total mass of a solution ) *100

Commercial bleaching solutions: 3.62% of sodium hypochlorite in water.

Question 11

What is:

Volume percentage?

Answer 11

(volume of a substance/total mass of a solution) *100

35% solution of ethylene glycol (antifreeze) used to cool engines

Question 12

What is:

Mass/volume percentage?

Answer 12

(Mass of a substance/volume of a solution) *100

Question 13

What is:

Parts per million (ppm)?

Answer 13

(no. of parts (in mass/volume) of the component / total no. of parts (in mass/volume) of all components) *10^6

Question 14

What is:

Mole fraction?

Answer 14

(no. of moles of the component/total no. of moles of all components)

Xa + Xb = 1

Question 15

What is:

Molarity?

Answer 15

no. of moles of the solute/ volume of the solution (L)

Also: percent x density x 10 / M2

Question 16

What is:

Molality?

Answer 16

no. of moles of solute/ mass of the solvent (Kg)

Question 17

What is:

Solubility?

Answer 17

The maximum amount of substance that can be dissolved in a specific amount of solvent at a particular temperature.

It depends on: the nature of the substances, temp. and pressure

Question 18

What is:

‘Like dissolved like’?

Answer 18

A solute will only dissolve in a solvent if the intermolecular forces in the two are similar.

Question 19

What is:

Dissolution?

Answer 19

When a solid solvent is added to a solute, some of it dissolves and the conc. of the solution increases.

Question 20

What is:

Crystallisation?

Answer 20

Some solute particles in the solution collide with the solid solute and get seperated out of the sollution.

Question 21

What is:

Saturation?

Answer 21

A solution in which no more solute can be dissolved at the same temp. and pressure.

Question 22

Effect of:

Temp. of the solubility of a solid in liquid?

Answer 22

(If endothermic) Increase in temp. = increase in solubility
(If exothermic) Increase in temp. = decrease in solubility

Question 23

Effect of:

Pressure on the solubility of solids in gases?

Answer 23

Pressure does not have any effect.

Question 24

Effect of:

Temp. on the solubility of gases in liquids?

Answer 24

(is an exothermic process) as temp. increases, the solubility decreases.

Question 25

# Effect of: Pressure of the solubility of gases in liquid?

Answer 25

As pressure increases, solubility increases

Question 26

# State: Henry's law:

Answer 26

( for gases in liquids) The vap. pressure of the gas above the soltuion ∝ the mole fraction of gas in the solution. P ∝ X P = Kh X | Pressure at STP = 1 bar = 0.987 atm.

Question 27

# List: How does Kh vary with temp., solubility and pressure?

Answer 27

As temp increases, Kh increases As solubility increases, Kh decreases As pressure increases, Kh decreases

Question 28

# List: Medical conditions associated with the solubility of gases in liquids:

Answer 28

- Bends - Anoxia

Question 29

# State: Raoult's law (for liq. in liq. solution) :

Answer 29

(for a solution of 2 volatile liquids), the partial pressure of each component above the solution is ∝ the mole fraction of that component in the solution. p1 ∝ X1 p2 ∝ X2

Question 30

# What is: Formula for total pressure?

Answer 30

P (total) = p1 + p2 = p1o + X2 (p2o - p1o)

Question 31

# State: Raoult's law ( for solid in liq. solutions)

Answer 31

(for a solution of a solid in a volatile liquid), the partial pressure of the liquid vapour ∝ its mole fraction in the solution p1∝ X1 p1 = p1o X1

Question 32

# What is: An ideal solution?

Answer 32

A solution that obeys Raoult's law over the entire range of concentrations. ΔH mix = 0 ΔV mix = 0 Ptotal = P1 + P2

Question 33

# List: Examples of ideal solutions:

Answer 33

- n hexane and n heptane - Bromoethane and chloroethane - Benzene and Toulene

Question 34

# What is: A non-ideal solution?

Answer 34

A solution that does not follow Raoutl's law for the entire range of concentration. Ptotal is greater than/lesser than P1 + P2

Question 35

# List: Types of non-ideal behaviour:

Answer 35

- Positive deviation: ΔH mix > 0 ΔV mix > 0 Ptotal > P1 + P2 - Negative deviation: ΔH mix < 0 ΔV mix < 0 Ptotal < P1 + P2

Question 36

# List: Examples of positive deviation:

Answer 36

- ethanol and acetone - cyclohexane and ethanol - carbon disulphide and acetone

Question 37

# List: Examples of negative deviation:

Answer 37

- chloroform and acetone - phenol and aniline - aniline and acetone

Question 38

# What is: An azeotrope?

Answer 38

Are solutions with the same concentration in the liquid and vapour phase. They boil at constant temp. and cannot be seperated by distillation.

Question 39

# List: Types of azeotropes:

Answer 39

- Minimum boiling azeotrope (show large +ve deviation from Raoult's law) ex// 95% ethanol in water by volume - Maximum boiling azeotrope (show large -ve deviation from Raoult's law) ex// 68% nitric acid and 32% water by mass

Question 40

# What is: A colligative property?

Answer 40

A property that depends only on the no. of solute particles relative to the total no. of particles in the solution.

Question 41

# List: Colligative properties:

Answer 41

- Relative lowering of vapour pressure - Boiling point - Depression of freezing point - Osmosis and osmotic pressure

Question 42

# What is: Boiling point?

Answer 42

The temp. at which the vapour pressure of the volatile liquid = the atmospheric pressure

Question 43

# What is: Freezing point?

Answer 43

Freezing point of the pure solvent = temp. at which the vap. pressure of the liq. solvent = the vap. pressure of the freezing solvent. Freezing point of the solution = temp. at which the vap. pressure of the solution ( liquid solvent + solute) = the vap. pressure of the solid solvent.

Question 44

# What is: Osmosis?

Answer 44

Flow of solvent from high conc. ---> low conc. or solvent ----> solution Dilute solution -----> conc. solution

Question 45

# What is: Osmotic pressure?

Answer 45

It is the extra pressure that has to be applied on the solution side to stop the slow of the solvent from the pure solvent to the solution across the semi-permeable membrane.

Question 46

# List: Examples of SPM:

Answer 46

- Pig's bladder - Cellophane

Question 47

# List: Types of solutions based on conc:

Answer 47

- Isotonic ( same conc. no osmosis) - Hypotonic ( low conc. (less than 0.9%) of solute, cell swells) - Hypertonic ( high conc. of solute, cell shrinks)

Question 48

# What is: Reverse osmosis?

Answer 48

Pressure (greater than osmotic pressure) is applied to the solution side to force the solvent to move fro the solution side to the solvent side through an SPM. | SPM used: cellulose acetate

Question 49

# Fill in: Water boils at:

Answer 49

100 celcius or 373.15 K

Question 50

# Fill in: Water freezes at:

Answer 50

0 celcius or 273.15 k

Question 51

# Fill in: Kf for water:

Answer 51

1.86 K/mol/kg