Question

1. a) Draw a vapour pressure (pA) vs composition (xA) graph for an ideal solution of A mixed with B.
b) Sketch a curve that you might see for a real solution where A interacts more strongly with itself than it does with B.
c) Label the region of this graph that follows Henry’s Law.
d) Will the Henry’s Law constant for A be larger or smaller than vapour pressure of pure A? Explain your answer in one sentence.
e) Label the region of the graph where the solution behaves like a ideal real solution.
f) Will the boiling point of the real solution be greater than or less than the boiling point of the corresponding ideal solution? Explain your reasoning in one sentence.
g) Will the activity of A in this solution be greater than or less than xA? Use the appropriate equation(s) to explain your answer.

2. If a person drinks a large amount of water very quickly, it is possible to exceed the rate of water removal by the kidney (~1 L/hour), essentially diluting the blood. The resulting osmotic pressure causes cells to swell. Fat and muscle cells have a capacity to adjust to this change in volume, but neurons in the brain do not have room to accommodate this size increase. (The skull is so densely packed, there is no room for swelling!) Consequently, as water enters neuronal cells, pressure is exerted on the brain, causing headache, fatigue, mental disorientation, and in severe cases, loss of consciousness and death. A healthy adult has 135 mM sodium chloride in 6.0 L of blood. Severe symptoms of water intoxication manifest when sodium concentrations are 100. mM and lower.
a) Assuming that the blood of a normally hydrated person is isotonic with cells (i.e. same osmotic pressure inside and outside), what is the osmotic pressure that is generated under conditions of severe water intoxication? (Body temperature is 37o C.)
b) To get an idea of how much pressure that is being imposed on the brain, calculate how far underwater you would have to descend to experience this amount of pressure. (The density of water is 1.0 kg/L.)
c) The freezing point of normal human blood is -2.0o C. Based on this value, what is the osmotic pressure of blood at 37o C? (Food for thought: how can we handle such a high osmotic pressure in the blood?)

Answer 1

1.

a) Draw a vapour pressure (pA) vs composition (xA) graph for an ideal solution of A mixed with B.

b) Sketch a curve that you might see for a real solution where A interacts more strongly with itself than it does with

c) Label the region of this graph that follows Henry’s Law.

Typically, less than 10%

so

d) Will the Henry’s Law constant for A be larger or smaller than vapour pressure of pure A? Explain your answer in one sentence.

It should be larger, since the interaciton between A is high

Please post all other multiple questions in multipl set of Q&A. We are allowed to answer to only one question per set of Q&A.