Answer one of the following three questions.

Value of this section: 10 marks

1. Methanol boils at 337.22K. The enthalpy of vaporization of methanol at this temperature is 35.27kJ/mol. The absolute entropy of liquid methanol at 298K is . Calculate the entropy of gaseous methanol at . [10 marks]
2. The solubility product of silver (I) iodide (AgI) is only at 298K. This is tiny so it is not generally necessary to use Debye-Hückel theory to compute the solubility of this compound. However, if other ions are present, they affect the ionic strength and so change the solubility. Compare the solubility of silver (I) iodide in pure water to its solubility in a 0.008mol/L solution of sodium nitrate ( ) in water. [10 marks]

   Notes: All sodium and nitrate salts are extremely soluble. You will need to use Debye-Hückel theory for the sodium nitrate/silver iodide mixture.

3. In class, we derived the equation

   

   Complete the derivation of the osmotic pressure equation from this point. [10 marks]

Useful information

To convert degrees Celsius to Kelvin, add 273.

Liquid water has a specific heat capacity of . Steam has a specific heat capacity of . The enthalpy of vaporization of water at its normal boiling point ( ) is 2257J/g.

1W = 1J/s

dE = dw + dq

H = E+PV

G = H-TS

with