Chapter 14, Problem 17STP

Interpretation Introduction

Interpretation:

From the given choices, the one which is not a colligative property needs to be identified.

Concept introduction:

Colligative properties are those properties of solutions, which entirely depend upon the number of solute particles (molecules or ions) dissolved in a known volume of solvent, but not at all on the nature (i.e., chemical composition or constitution) of those solute particles. Here the solute is invariably taken as non-volatile. Colligative properties are as follows:

1. Lowering of vapor pressure
2. Osmotic pressure
3. Elevation of boiling point
4. Depression of freezing point

The colligative properties the properties of dilute solution specifically which behaved as an ideal gas solution.

Answer to Problem 17STP

The increase in vapor pressure is NOT a Colligative property.

When a solute added to the solvent, the vapor pressure is lowered. The lowering of vapor pressure is due to the number of solute particles in solution and it is a colligative property of solutions. So, vapor pressure increases which is given in option c is NOT a colligative property as Lowering of vapor pressure is a colligative property.

Reasons for incorrect options: As vapor pressure lowering is colligative property. And in the given options, vapor pressure increase is given as colligative property which is not correct. While the other options that is

a. boiling point elevation

b. freezing point depression

d. osmotic pressure

e. heat of solution,

are colligative properties so, these are not true as not a colligative property.

Explanation of Solution

When a solute added to the solvent, the vapor pressure is lowered. The lowering of vapor pressure is due to the number of solute particles in solution and it is a colligative property of solutions. So, vapor pressure increases which is given in option c is NOT a colligative property as Lowering of vapor pressure is a colligative property.

Conclusion

Reasons for incorrect options: As vapor pressure lowering is colligative property. And in the given options, vapor pressure increase is given as colligative property which is not correct. While the other options that is

a. boiling point elevation

b. freezing point depression

d. osmotic pressure

e. heat of solution,

are colligative properties so, these are not true as not a colligative property.