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GAMSAT March 2016 COPY > CHM 5 - Solution Chemistry > Flashcards

CHM 5 - Solution Chemistry Flashcards

1
Q

Name a Universal solvent

A

Water.

A universal solvent is a pure substance or a one component system.

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2
Q

What is a solution ?

A

A sample of matter that is homogenous, but unlike a pure substance, the composition of a solution can vary within relatively wide limits.

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3
Q

What is supersaturation ?

A

A state of a solution that contains more of a dissolved material than could be dissolved by the solvent under normal circumstances.

E.g. Heat sucrose and water, leads to a supersaturated solution.

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4
Q

Explain the term Endothermic

A

Absorbing heat

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5
Q

Explain the term Exothermic

A

Gives out heat

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6
Q

Explain the term enthalpy

A

A measure of the total energy of a system.

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7
Q

Describe the initial step of solution formation

A

The breakage of intermolecular forces amongst the solutes and solvents seperately (Endothermic).

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8
Q

Describe the second step in solution formation

A

Reforming of intermolecular interations between solute and solvent.

(Exothermic)

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9
Q

What effect does enthalpy have on the stability of a formed solution ?

A

Increased enthalpy or positive solution heat means more enthalpy in the system, therefore the formed solution is less stable and has weaker bonds.

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10
Q

How do you determine the solvent in a solution equation ?

A

The component of the solution that is in the same phase as the reactants is the solvent.

(N.B. If they are in the same phase, the component present in the larger amount is the solvent.)

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11
Q

What is a colligative property ?

A

The property of a solution that depends on the number of particles present, and not the nature of the chemical species present.

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12
Q

What is the Van’t Hoff factor (i) ?

A

The ratio between the actual concentration of the particles produced when the substance is dissolved, and the concentration of a substance as calculated from its mass.

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13
Q

Why is the Van’t Hoff factor (i) used ?

A

This factor is used as a measure of the effect of colligative properties on a solution.

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14
Q

Give 3 examples of Colligative properties ?

A
  1. Osmotic pressure
  2. Relative lowering in vapour pressure
  3. Elevation of boiling point
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15
Q

What is the Van’t Hoff factor for non-ionic solutions ?

A

1

As particles are undissociated

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16
Q

What is the Van’t Hoff factor for ionic solutions ?

A

Usually dependent on the number of ions dissolved in the solution e.g. NaCl = 2, CaCl2 = 3

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17
Q

What is the basis of Raoult’s law ?

A

If you have a solvent which you can add a solute to, the solute and solvent start to interact, therefore the vapour pressure will be lowered because there are fewer molecules to enter the vapour phase

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18
Q

What is the equation for Raoult’s law ?

A
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19
Q

What is the difference between the vapour-pressure curve of a dilute solution, and that of a pure solvent ?

A

A solution has an elevated boiling point and a depressed freezing point

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20
Q

What is the relationship between the vapour pressure and mole fraction of a solvent ?

A

They are directly proportional

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21
Q

What do colligative properties depend on ?

A

The number of particles present

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22
Q

What is Osmotic pressure ?

A

The equilibrium distribution of solvent across semi-permeable membranes separated by two compartments

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23
Q

What is a semi-permeable membrane in terms of solution chemistry ?

A

When a solvent and solution are separated by a membrane permeable only to molecules of solvent, it allows the solvent to pass and not the solute.

24
Q

What is the difference between molarity and molality ?

A

Molalities are more convenient than molarities in experiments that involve significant temperature changes. Because the volume of a solution increases when its temperature increases, heating makes the solutions molarity go down- but the molality, which is based on masses rather than volumes, remains unchanged.

25
Q

What is molarity ?

A

Moles of solute per litre of solution

26
Q

What is molality ?

A

Moles of solute per kg of solvent

27
Q

What is the name for positively charged ions ?

A

Cations

28
Q

What is the name for negatively charged ions ?

A

Anions

(A Negative Ion)

29
Q

Name 9 common anions that can form in water, ending in -ide ?

A
  • Flouride F-
  • Chloride Cl-
  • Bromide Br-
  • Iodide I-
  • Oxide O2-
  • Sulfide S2-
  • Nitride N2-
  • Hydroxide OH-
  • Cyanide CN-
30
Q

Name 7 common anions that can form in water, ending in -ate ?

A
  • Nitrate NO3-
  • Nitrite NO2-
  • Carbonate CO32-
  • Sulfate SO42-
  • Phospahte PO43-
  • Acetate CH3CO2-
  • Permanganate MnO4-
31
Q

Name 7 common cations that end in -ium ?

A
  • Sodium Na+
  • Lithium Li+
  • Potassium K+
  • Ammonium NH4+
  • Hydronium H3O+
  • Calcium Ca2+
  • Magnesium Mg2+
32
Q

Name 3 common cations that do NOT end in -ium ?

A
  • Hydrogen H+
  • Iron (II) Fe2+
  • Iron (III) Fe3+
33
Q

Define solubility in terms of solution chemistry

A

The amount of substance (solute) known to dissolve into a particular amount of solvent at a given temperature.

34
Q

What does solubility of a solvent depend on ?

A
  • The entropy change of solubilization
  • The types of intermolecular forces present
35
Q

What is solvation or dissolution ?

A

The process of interaction between solute and solvent molecules, which occurs when intermolecular forces between solute and solvent are stronger than those between solute particles themselves.

36
Q

How would you predict solubility ?

A

“Like dissolves like” E.g. Ionic and Polar solutes are soluble in polar solvents, and non-polar solutes are soluble in non-polar solvents

37
Q

Name 8 ways in which solution concentrations can be expressed ?

A
  1. Molarity (M)
  2. Molality (m)
  3. Normality (N)
  4. Density (p)
  5. Osmole (Osm)
  6. Osmolarity (Osm/L)
  7. Osmolality (Osm/kg)
  8. Mole Fraction
38
Q

Describe dilution

A

When solvent is added to a solution containing a certain concentration of solute it becomes diluted to produce a solution of a lower solute concentration.

39
Q

What is the equation for expressing a dilution ?

A
40
Q

What is an electrolyte ?

A

Any solute that dissolves in water to give a solution that contains ions, and therefore can conduct electricity, is an electrolyte

41
Q

Describe a strong electrolyte

A

When dissociation is strong, extensive and irreversible

42
Q

Describe a weak electrolyte

A

When dissociation is weak, incomplete and reversible.

43
Q

Give 3 examples of strong electrolytes ?

A
  1. Salts (NaCl)
  2. Strong acids (HCl)
  3. Strong bases (NaOH)
44
Q

Give 5 examples of weak electrolytes

A
  1. Weak acids (CH3COOH)
  2. Weak bases (NH3)
  3. Complexes (Fe[CN]6)
  4. Tap water
  5. Soluble organic compounds
45
Q

Give two examples of non-electrolytes

A
  1. De-ionized water
  2. Soluble organic compounds (E.g. Sugars)
46
Q

What is the effect of temperature on solubility ?

A

As temperature increases, the solubility of most salts increases.

Solubility of gases decreases as temperature increases.

47
Q

What is meant by Ksp ?

A

This is the solbility product.

The precipitate has a definite solubility (even if “insoluble” e.g. Ag in H2O) that will be present at a given temperature (at equilibrium).

48
Q

What is the equilibrium expression for Ksp in AgCl ?

A

AgCl (s) ⇔ Ag+ (aq) + Cl- (aq)

Ksp = [Ag+] [Cl-]

49
Q

What would a low Ksp indicate ?

A

Little solubility product, therefore a low level of solubility.

50
Q

Describe the common ion effect of solubility ?

A

If there is an excess of one ion over the other, the concentration of the ‘other’ is suppressed.

51
Q

What is meant by Qsp ?

A

The ion product at any point, not just at equilibrium (Ksp)

52
Q

What happens if Qsp < Ksp ?

A

The solution is unsaturated and no precipitate will form.

53
Q

What happens if Qsp = Ksp ?

A

The solution is saturated and at equilibrium

54
Q

What happens if Qsp > Ksp ?

A

The solution is supersaturated and unstable. A solid salt will precipitate until ion product once again = Ksp.

55
Q
A

GAMSAT March 2016 COPY (26 decks)

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