A student investigates the rate of decomposition of hydrogen peroxide solution:
2H2O2→2H2O+O2 2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2 2H2O2→2H2O+O2The student uses a conical flask connected to a gas syringe to collect the oxygen gas.
The student keeps the amount, in moles, of H2O2\text{H}_2\text{O}_2H2O2 in the solution constant at the start of each experiment.
State two properties of the solution that he should keep the same to ensure that the initial amount of H2O2\text{H}_2\text{O}_2H2O2 is the same in each experiment.
The student carries out the experiment five times using a different solid each time to see how effective each solid is as a catalyst.
He records the time taken to collect 80 cm380\text{ cm}^380 cm3 of oxygen in the gas syringe.
| Solid | Time to collect 80 cm380\text{ cm}^380 cm3 of oxygen (seconds) |
|---|---|
| P | 68 |
| Q | 24 |
| R | no oxygen collected |
| S | 8 |
| T | 42 |
(i) Which solid does not seem to act as a catalyst?
(ii) Which solid is the most effective catalyst?
In the first experiment, the student added 2.0 g2.0\text{ g}2.0 g of solid P.
Describe what he could do with the contents of the conical flask at the end of the experiment to show that solid P was acting as a catalyst, and not as a reactant.
The student repeats the experiment using two new solids, X and Y. This time, he records the volume of oxygen collected at 101010-second intervals.
The results are shown in the table below:
| Time (seconds) | Volume of oxygen collected for Solid X (cm3\text{cm}^3cm3) | Volume of oxygen collected for Solid Y (cm3\text{cm}^3cm3) |
|---|---|---|
| 0 | 0 | 0 |
| 10 | 48 | 24 |
| 20 | 68 | 43 |
| 30 | 76 | 58 |
| 40 | 80 | 69 |
| 50 | 80 | 76 |
| 60 | 80 | 80 |
(i) Calculate the average rate of oxygen production for Solid Y during the first 20 seconds20\text{ seconds}20 seconds of the reaction.
(ii) Estimate the volume of oxygen collected after 35 seconds35\text{ seconds}35 seconds for Solid Y.
(iii) Use the data to explain how it shows that the reaction is faster with Solid X than with Solid Y.
