A mixture of gases reacts faster as its temperature increases.
Which row explains this?
| The activation energy remains unchanged | More particles have energy equal to or above the activation energy | There is an increase in the rate of successful collisions | |
|---|---|---|---|
| A | false | false | false |
| B | true | true | true |
| C | false | true | true |
| D | true | false | false |
Correct Answer: \( \boxed{\mathrm{B}} \)
Increasing the temperature does not change the activation energy of the reaction.
However, a greater proportion of particles have kinetic energies equal to or greater than the activation energy.
As a result, the number of successful collisions per unit time increases, so the reaction rate increases.
Therefore, the correct answer is (B).
Which reaction pathway diagram shows an endothermic reaction that occurs in two steps and in which the second step of the reaction is likely to be faster than the first?
Correct Answer: \( \boxed{\mathrm{C}} \)
An endothermic reaction has products at a higher energy level than the reactants.
A two-step reaction has two activation energy peaks.
The second step is faster than the first when its activation energy is lower than that of the first step.
Diagram C shows:
Therefore, the correct answer is (C).
The reversible reaction between methanol and ethanoic acid liquids is catalysed by adding a small volume of concentrated sulfuric acid.
Two statements about this reaction are listed.
1 The sulfuric acid is a homogeneous catalyst.
2 The sulfuric acid lowers the activation energy of the reverse reaction.
Which statements are correct?
Correct Answer: \( \boxed{\mathrm{A}} \)
Concentrated sulfuric acid is in the same liquid phase as methanol and ethanoic acid, so it acts as a homogeneous catalyst.
A catalyst provides an alternative reaction pathway with a lower activation energy for both the forward and reverse reactions.
Therefore, both statements are correct, so the correct answer is (A).
