Changing the pressure on the reaction
3 marks · EasyThe table shows the completion time for a reaction between two gases at different pressures.
| Pressure / kPa | Completion time / min |
|---|---|
| 80 | 20 |
| 160 | 10 |
| 240 | 6.7 |
Describe the relationship between pressure and completion time for this reaction.
Explain, using particle theory, why increasing the pressure causes this effect.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) As pressure increases, completion time decreases. · must show completion time decreases as pressure increases
(b) Increasing the pressure pushes gas particles closer together, causing them to collide more often, so the reaction goes faster. · must show particles closer together, more frequent collisions
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States that higher pressure results in a shorter completion time or faster reaction.
B2 (b) · 1 mark · Mentions that gas particles are closer together as pressure increases.
B3 (b) · 1 mark · Explains that more frequent collisions increase the rate of reaction.
Worked solution
a) As pressure increases, the time taken to complete the reaction decreases.
b) Increasing pressure pushes gas particles into a smaller volume, so they are closer together and collide more often, making the reaction faster.