Question 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 explain.
Question 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.
Question 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.