Question

PART C

6. The rate of formation of ethylene oxide was measured in a 1 m reaction vessel as a function of the pressure of O2, at a constant pressure of 827 kPa of ethylene oxide and a reaction temperature of 300 °C. The data is presented in the table below. Pressure poz/kPa Ethylene oxide formation rate / umol s1 207 65 414 105 127 620 828 1035 1241 135 139 140 a) Plot a graph of the rate of formation of ethylene oxide versus the pressure of O2 at a constant pressure of ethylene oxide. (3 marks) b) State whether ethene epoxidation proceeds via a Langmuir- Hinshelwood or an Eley-Rideal mechanism on this catalyst and give your reasoning (4 marks) c) Calculate an approximate rate constant for the reaction in units of s (7 marks)

Answer 1

The plot of ethylene oxide formation rate versus P_O2 can be drawn as follows.

160 140 120 100 80 60 40 -20 400 1400 0 200 600 800 1000 1200 P (kPa) 02 Ethylen oxide formation rate (umol.s)

The plot resembles the Eley-Rideal mechanism because it is not a straight line but there is hump.