Solutions Flashcards

Chapter 6

1
Q

What is:

Brass?

A

A mixture of copper and zinc

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2
Q

What is:

German silver?

A

A mixture of copper, zinc and nickel

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3
Q

What is:

Bronze?

A

A mixture of copper and tin

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4
Q

Fill in:

1ppm of flouride in water —-

A

—— prevents tooth decay

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5
Q

Fill in:

1.5 ppm of flouride in water—–

A

——- mottles teeth

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6
Q

Fill in:

Any concentration of flouride in water above that—–

A

—— is commonly used as rat poison

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7
Q

Fill in:

A solution consists of——-

A

———- a solute and a solvent

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

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8
Q

What is:

A binary solution?

A

A binary solution contains only 2 components

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9
Q

List:

Types of binary solutions:

A
  • Gaseous solutions
  • Liquid solutions
  • Solid solutions
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10
Q

What is:

Mass percentage?

A

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

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

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11
Q

What is:

Volume percentage?

A

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

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

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12
Q

What is:

Mass/volume percentage?

A

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

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13
Q

What is:

Parts per million (ppm)?

A

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

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14
Q

What is:

Mole fraction?

A

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

Xa + Xb = 1

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15
Q

What is:

Molarity?

A

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

Also: percent x density x 10 / M2

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16
Q

What is:

Molality?

A

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

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17
Q

What is:

Solubility?

A

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

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18
Q

What is:

‘Like dissolved like’?

A

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

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19
Q

What is:

Dissolution?

A

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

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20
Q

What is:

Crystallisation?

A

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

21
Q

What is:

Saturation?

A

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

22
Q

Effect of:

Temp. of the solubility of a solid in liquid?

A

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

23
Q

Effect of:

Pressure on the solubility of solids in gases?

A

Pressure does not have any effect.

24
Q

Effect of:

Temp. on the solubility of gases in liquids?

A

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

25
Q

Effect of:

Pressure of the solubility of gases in liquid?

A

As pressure increases, solubility increases

26
Q

State:

Henry’s law:

A

( 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.

27
Q

List:

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

A

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

28
Q

List:

Medical conditions associated with the solubility of gases in liquids:

A
  • Bends
  • Anoxia
29
Q

State:

Raoult’s law (for liq. in liq. solution) :

A

(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

30
Q

What is:

Formula for total pressure?

A

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

31
Q

State:

Raoult’s law ( for solid in liq. solutions)

A

(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

32
Q

What is:

An ideal solution?

A

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

33
Q

List:

Examples of ideal solutions:

A
  • n hexane and n heptane
  • Bromoethane and chloroethane
  • Benzene and Toulene
34
Q

What is:

A non-ideal solution?

A

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

35
Q

List:

Types of non-ideal behaviour:

A
  • Positive deviation:
    ΔH mix > 0
    ΔV mix > 0
    Ptotal > P1 + P2
  • Negative deviation:
    ΔH mix < 0
    ΔV mix < 0
    Ptotal < P1 + P2
36
Q

List:

Examples of positive deviation:

A
  • ethanol and acetone
  • cyclohexane and ethanol
  • carbon disulphide and acetone
37
Q

List:

Examples of negative deviation:

A
  • chloroform and acetone
  • phenol and aniline
  • aniline and acetone
38
Q

What is:

An azeotrope?

A

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

39
Q

List:

Types of azeotropes:

A
  • 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
40
Q

What is:

A colligative property?

A

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

41
Q

List:

Colligative properties:

A
  • Relative lowering of vapour pressure
  • Boiling point
  • Depression of freezing point
  • Osmosis and osmotic pressure
42
Q

What is:

Boiling point?

A

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

43
Q

What is:

Freezing point?

A

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.

44
Q

What is:

Osmosis?

A

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

45
Q

What is:

Osmotic pressure?

A

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.

46
Q

List:

Examples of SPM:

A
  • Pig’s bladder
  • Cellophane
47
Q

List:

Types of solutions based on conc:

A
  • Isotonic ( same conc. no osmosis)
  • Hypotonic ( low conc. (less than 0.9%) of solute, cell swells)
  • Hypertonic ( high conc. of solute, cell shrinks)
48
Q

What is:

Reverse osmosis?

A

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