CAIE A-Level Chemistry AS 8.3 Homogeneous and Heterogeneous Catalysts Questions
Practise explaining catalysis through an alternative lower-EA mechanism, energy profiles and Boltzmann distributions.
- Syllabus
- 2028–2030
- Course
- Chemistry 9701
- Level
- AS
Exam points
- state that a catalyst provides a different mechanism with a lower activation energy
- show the catalysed pathway with lower peak height but unchanged reactant, product and ΔH levels
- use the larger Boltzmann area above the lower EA to explain the increased effective-collision frequency
Covered syllabus points
Question 1
The Boltzmann distribution for the hydrogenation of an alkene at a particular temperature in the absence of a catalyst is shown.
Which row correctly describes the effects of adding a nickel catalyst to the reaction vessel?
the shape of the Boltzmann distribution
activation energy,
changes
decreases
changes
increases
does not change
decreases
does not change
increases
Question 2
Gas Q decomposes slowly at room temperature.
The Boltzmann distribution curve for gas Q at room temperature is shown.
Which change occurs when a catalyst is added to gas Q ?
A
The peak of the curve moves to the right on the diagram.
B
The number of particles with enough energy to decompose increases.
C
The kinetic energy of the unreacted particles increases.
D
The value of decreases, moving the vertical dotted line to the right on the diagram.
Question 3
Two experiments are carried out to study the reaction between zinc and sulfuric acid.
experiment 1 Small lumps of zinc are added to excess dilute sulfuric acid.
experiment 2 The reaction is carried out at a lower temperature and with one other change.
Both experiments produce the same total volume of gas and are completed in the same time.
What is the second change made in experiment 2 ?
A
A catalyst is added.
B
A greater mass of zinc is added.
C
A greater volume of sulfuric acid is added.
D
Larger lumps of zinc are used.
All question bank results loaded