A student investigated the rate of the catalytic decomposition of hydrogen peroxide:
2H2O2(aq)→2H2O(l)+O2(g) 2\text{H}_2\text{O}_2(\text{aq}) \rightarrow 2\text{H}_2\text{O}(\text{l}) + \text{O}_2(\text{g}) 2H2O2(aq)→2H2O(l)+O2(g)using manganese(IV) oxide as a catalyst. The oxygen gas evolved was collected over water in a graduated measuring cylinder.
The student recorded the time taken to collect exactly 54 cm3 of oxygen gas. The table below shows the calculated rates of reaction for each of the four trials.
| Trial | Rate of reaction in cm3/s\text{cm}^3/\text{s}cm3/s |
|---|---|
| Trial 1 | 1.18 |
| Trial 2 | 1.22 |
| Trial 3 | 0.62 |
| Trial 4 | 1.20 |
Determine the mean time taken to collect 54 cm3 of oxygen gas. Do not include any anomalous results in your calculation.
Use the equation:
mean rate of reaction=volume of gas collectedmean time taken \text{mean rate of reaction} = \frac{\text{volume of gas collected}}{\text{mean time taken}} mean rate of reaction=mean time takenvolume of gas collected26 exam-style questions on AQA GCSE Chemistry 6.1 Rate of reaction, covering 6.1.1 Calculating rates of reactions, 6.1.2 Factors which affect the rates of chemical reactions, 6.1.3 Collision theory and activation energy, and 6.1.4 Catalysts. Each one has a worked solution and a mark scheme showing where the marks go.