ChemIIA 2012 final.pdf
Chemistry IIA, IIA(Ecochem), IIA(Mol Drug Des), IIA(Nanosci Mat) June 2012
The natural logarithm of the rate constant (ln k) is plotted against the reciprocal of the absolute temperature for
the decomposition of N2O. The best-fit linear curve has an equation shown below in the plot.
y = -30317x + 29.346
1/T (K )
What is the value of the activation energy of this reaction?
[Total for question 4 = 3 marks]
Briefly explain why the following rate law for the chemical reaction below is unlikely.
2NO2(g) + F2(g) 2NO2F(g)
Rate = k[NO2]2[F2], where k is the rate constant
In fact, the experimentally determined rate law for the reaction is Rate = k[NO2][F2]. Propose a simple
and acceptable mechanism that satisfies the rate law.
[Total for question 5 = 3 marks]
The decomposition of hydrogen iodide,
2HI(g) H2(g) + I2(g)
has rate constants of 9.51 x 10-9 L/mols at 500 K and 1.10 x 10-5 L/mols at 600 K. Calculate the activation
energy. Hint: the frequency factor A is independent of temperature.
[Total for question 6 = 4 marks]
[Total for Part B = 30 marks]
- - - END of PART B - - -
Course ID. 104311, 104312, 104313, 104314
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