Exam code: XCH11
What is the effect of increasing temperature on the average energy of the particles in a reaction and on the activation energy of the reaction?
|
| Effect on the average energy | Effect on the activation energy |
☐ | A | unchanged | decreased |
☐ | B | unchanged | unchanged |
☐ | C | increased | decreased |
☐ | D | increased | unchanged |
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1 markThe graph shows how the concentration of iodine changes with time in a reaction.
What is the value for the rate of reaction, in mol dm−3 s−1, at 8 seconds?
0.01
0.02
0.03
0.25
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The solid line on the graph below shows the Maxwell–Boltzmann distribution for an uncatalysed reaction. Ea is the activation energy of this reaction.
Which row shows the correct Maxwell–Boltzmann curve and activation energy for the reaction at a higher temperature with a catalyst?
|
| Maxwell-Boltzmann curve | Activation energy |
☐ | A | X | W |
☐ | B | X | Z |
☐ | C | Y | W |
☐ | D | Y | Z |
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Which conditions give the highest yield for the forward reaction?
NH4Cl (s) ⇌ NH3 (g) + HCl (g) ΔH = +176 kJ mol−1
high temperature, high pressure
high temperature, low pressure
low temperature, high pressure
low temperature, low pressure
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Nitrogen dioxide and dinitrogen tetroxide exist in equilibrium.
2NO2 (g) ⇌ N2O4 (g) brown gas colourless gas
When an equilibrium is set up in a gas syringe, the mixture is pale brown.
When the mixture is compressed the colour becomes
darker
lighter
darker and then lighter
lighter and then darker
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