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Pharmaceutics Year 2 > Section 6 - Colligative Properties > Flashcards

Section 6 - Colligative Properties Flashcards

1
Q

What do colligative properties depend on?

A

Number of solute particles in a solution

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2
Q

What is included in colligative properties?

A
  • Osmotic pressure
  • Vapor pressure lowering
  • Boiling point elevation
  • Freezing point depression
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3
Q

What is a one molar (1M) solution?

A

One gram-molecular weight of substance dissolved to a final volume of 1000 mL

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4
Q

What is a one molal (1m) solution?

A

One gram-molecular weight of substance dissolved in 1000 g of water

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5
Q

Is a molal solution temperature sensitive?

A

No

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6
Q

What is a one normal (1N) solution?

A

The equivalent weight (one gram-molecular weight/valence) of substance dissolved in water to a final volume of 1000 mL

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7
Q

What is normal saline?

A

0.9% solution of NaCl

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8
Q

When saline is w/ the fluid of a cell, is it hypo, hyper, or isotonic?

A

Isotonic

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9
Q

What is osmotic pressure?

A

The amount of pressure which must be applied to the more concentrated side to stop passage of solvent molecules

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10
Q

Solutions for injection should be made __tonic whenever possible

A

Isotonic

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11
Q

What does semi-permeable mean?

A

Only solvent molecules can pass through the membrane (not solute molecules)

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12
Q

In a biological system, what is the tonicity of the bathing fluid?

A

Isotonic to the fluid inside of the cells

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13
Q

What does Raoult’s law show?

A

The effect of solute concentration on vapor pressure

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14
Q

What is Raoult’s law and what does each value correspond to?

A

Pa = Pa0 (1 - xb)

  • Pa = vapor pressure of solution
  • Pa0 = vapor pressure of pure solvent
  • Xb = mole-fraction of solute
  • Xa = mole-fraction of solvent (Xa + Xb = 1)
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15
Q

What is the vapor pressure of pure water at 20 C?

A

17.54 mmHg

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16
Q

What is boiling point (with respect to pressure)?

A

Temperature at which vapor pressure of a liquid is equal o the external atmospheric pressure of 760 mmHg

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17
Q

What happens to vapor pressure when a non-volatile solute is added, and what does this mean for boiling point?

A
  • Vapor pressure is lowered

- Solution must be brought to a higher temp than the pure solvent to reach the boiling point

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18
Q

What is freezing point (with respect to pressure)?

A

Temperature where solid and liquid phases of a solution are in equilibrium at a pressure of 1 atmosphere

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19
Q

What is the formula for boiling point elevation?

A
  • Delta Tb = (Kb)(m)
  • Tb = increase in temperature required
  • Kb = proportionality constant
  • m = molal strength of the solute
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20
Q

What is the boiling point proportionality constant for water?

A

0.515 C

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21
Q

What is the formula for freezing point depression?

A
  • Delta Tf = (Kf)(m)
  • Tf = lowering of freezing point
  • Kf = proportionality constant
  • m = molal strength of solute
22
Q

What is the freezing point proportionality constant for water?

A

1.858 C

23
Q

Identical molal solutions of non-electrolytes have the same _____

A

Colligative properties

24
Q

How many grams of dextrose dissolved in 1000 g of water will produce a 0.1 molal solution?

A

19.8 g

25
Q

How many grams of mannitol dissolved in 1000 g of water will produce a 0.1 molal solution?

A

18.2 g

26
Q

How many grams of glycerin dissolved in 1000 g of water will produce a 0.1 molal solution?

A

9.2 g

27
Q

Why are colligative properties different for identical molal electrolyte solutions?

A

Each ion will act as a particle, so the colligative properties will be a function of the degree of ionization

28
Q

When in solution, how many particles will Na3citrate produce?

A

Four particles

29
Q

What is a millimole?

A

1/1000 of the molecular weight in grams

30
Q

What is the equivalent weight?

A

The molecular weight of the substance divided by the valence

31
Q

What is milliequivalents related to?

A

Total number of ionic charges

32
Q

What unit is used to expressed osmotic pressure?

A

mOsmol

33
Q

What amount of dextrose will produce one mOsmol?

A

1 mmol b/c dextrose in a non-electrolyte

34
Q

What will 1 mmol of NaCl be in mOsmol?

A

2 (assuming 100% ionization, will dissociate into 2 ions)

35
Q

What happens to electrolyte solutions as concentration increases (with respect to dissociation and osmolarity)?

A

More interactions btwn solute particles, so electrolyte dissociation is less than 100%, so measured osmolarity will be less than calculated

36
Q

What is the osmolarity of an isotonic solution?

A

275-320 mOsmol/L

37
Q

What is the difference between osmolarity and osmolality?

A
  • Osmolarity = milliosmoles of solute per litre of solution

- Osmolality = number of milliosmoles per kilogram of solvent

38
Q

For which formulations are isotonic solutions better tolerated?

A
  • Ophthalmic
  • Nasal
  • Vaginal
  • Parenteral
39
Q

How can you prepare isotonic solutions?

A

Using data derived from colligative properties of the solution

40
Q

What temperature does serum freeze at?

A

-0.52 C

41
Q

How can you determine how much of a substance dissolved in 1000g of water will give an isotonic solution?

A
  • Use freezing point depression
  • Know that serum freezes at 0.52 C
  • Formula = (0.52 * MW) / (1.86 * i) = g of solute in 1000 g water
  • i = dissociation factor
42
Q

What can you determine from knowing that a solution of 55.5 g dextrose monohydrate in 1000 g of water has a freezing point depression of 0.52 C?

A

It is isotonic

43
Q

What happens to degree of dissociation w/ increasing concentration?

A

Degree of dissociation decreases, so need to use a dissociation factor

44
Q

What is the first step in making 100 mL of an isotonic solution of atropine sulfate 1%?

A

Determine how much the atropine contributes towards the tonicity of the solution

45
Q

How will the tonicities compare of 2 solutions, each prepared w/ 1 gram-molecular weight divided by it’s i value and dissolved in 1000 g of water?

A

Tonicity will be the same

46
Q

What is the i value for a substance that dissociates into 2 particles?

A

1.8

47
Q

What is the i value for a substance that dissociates into 3 particles?

A

2.6

48
Q

What is the i value for a substance that dissociates into 4 particles?

A

3.4

49
Q

What method should be used to make an isotonic solution if the final product is to be buffered and what does this method include?

A
  • Volume adjustment
  • Determine the quantity of water needed to make an isotonic solution for a given amount of drug, followed by dilution w/ an isotonic solution to make up the volume
50
Q

How do you do volume adjustment calculations?

A

Multiply weight of drug by its sodium chloride equivalent (E) = quantity of sodium chloride osmotically equivalent to weight per gram of drug

51
Q

What is an easy way to make an isotonic solution?

A

Dissolve weight of drug * E in volume (mL) of water

52
Q

Will adding together 2 isotonic solutions produce an isotonic solution?

A

Yes

Pharmaceutics Year 2 (17 decks)

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