# Chapter 06

## Instructions

### Question 1

The partial molar volumes of water, H2O, and methanol, CH3OH, are 17.8 cm3 mol-1 and 38.4 cm3 mol-1 respectively at 25.0°C for dilute mixtures of methanol in water. Calculate the total volume when 15 cm3 of methanol is added to 250 cm3 of water at this temperature. The density of methanol is 0.791 g cm-3.

### Question 2

Calculate the change in the chemical potential of a perfect gas when it expands isothermally at a temperature of 20.0°C so that its volume doubles.

### Question 3

Calculate the entropy change when 2.0 mol of a perfect gas A and 3.0 mol of a perfect gas B mix spontaneously.

### Question 4

Which of the following statements is always true for a liquid mixture of two components A and B in equilibrium with a mixture of their vapours?

A(l) = μB(l) and μA(g) = μB(g)

### Question 5

A solution is prepared by dissolving 5.32 g of benzene, C6H6, in 93.2 g of toluene, C6H5CH3, at 25°C. The vapour pressures of pure benzene and pure toluene are 12.7 kPa and 3.8 kPa at this temperature. Use Raoult's law to determine the partial vapour pressure of each of the two components for the mixture.

### Question 6

The vapour pressure of bromobenzene, C6H5Br, above an ideal-dilute aqueous solution of molality 0.092 mol kg-1 is 23.6 kPa. Calculate the Henry's law constant of bromobenzene.

### Question 7

Which of the following statements is true for an ideal-dilute solution?

### Question 8

Calculate the minimum partial pressure of nitrogen that is necessary to achieve an aqueous ideal-dilute solution of concentration 1.00 mmol dm-3. The Henry's law constant for nitrogen in water is 156 kPa m3 mol-1.

### Question 9

Calculate the change in the normal boiling temperature of an aqueous solution made by dissolving 15.0 g of bromobenzene, C6H5Br, in 250 cm3 of water. The ebullioscopic constant of water is 0.51 K kg mol-1.

### Question 10

Calculate the osmotic pressure exerted by an aqueous solution of sucrose, C12H22O11, of mass concentration 6.51 g dm-3 at 20°C. The osmotic virial coefficient for dilute aqueous solutions of sucrose at this temperature is 0.382 dm3 mol-1.