problem 1: The oxidation of oxalic acid by chlorine:

Cl₂(aq) + (COOH)₂(aq) = 2 CO₂(g) + 2 Cl^-(aq) + 2 H + (aq)

follows the rate law d[CO₂]/dt = k[Cl₂][(COOH)₂]/[H+]2[Cl^-]₂

a) Determine the overall order of the reaction? What is the order with respect to Cl₂? CO₂? Cl^-?

b) How is the rate of production of CO₂ associated to the rate of loss of Cl₂?

c) What rate law would be predicted if one supposes that rate laws can be predicted from stoichiometry? Is this supposition valid in this case? In brief describe.

problem 2: You studied the separation of 4 isomeric alcohols in the gas chromatography experiment. The given peak widths and elution times were observed in a typical run at 60ºC:

Peak number    Elution time (min)    peak width (min)
1                              1.35                         0.10
2                              2.53                         0.19
3                              3.36                         0.23
4                              4.78                         0.30

a) Show whether the peak widths follow the predictions of diffusion theory.

b) Predict the width of a peak which elutes at 6.0 min.

problem 3: The given table gives some significant points on the pressure-temperature phase diagram of nitrogen:

                                     p(atm)         T(K)
triple point                    0.123          63.15
critical point                  33.3978      126.19
normal boiling point      1.00000      77.35
normal melting point     1.0000        63.29

The density of solid nitrogen is 1.03 g/ml and that of liquid nitrogen is 0.808 g/ml.

a) Sketch the phase diagram of nitrogen.

b) Is sublimation possible with nitrogen? Under what conditions?

c) Assume that nitrogen is used to calibrate a thermocouple. What temperature will be used as the calibration point? Justify your preference.