Manganese(IV) oxide acts as a catalyst to speed up the decomposition of hydrogen peroxide solution into water and oxygen gas.
2H2O2(aq)→2H2O(l)+O2(g) \mathrm{2H_2O_2(aq) \rightarrow 2H_2O(l) + O_2(g)} 2H2O2(aq)→2H2O(l)+O2(g)A student investigated the rate of this reaction using the following method:
- Add 50 cm350\text{ cm}^350 cm3 of 2.4 mol/dm32.4\text{ mol/dm}^32.4 mol/dm3 hydrogen peroxide solution to a conical flask.
- Add 0.5 g0.5\text{ g}0.5 g of manganese(IV) oxide powder to the flask.
- Immediately place the conical flask on a digital balance and start a timer.
- Record the total mass lost from the conical flask at regular intervals.
Explain how the manganese(IV) oxide catalyst increases the rate of decomposition of hydrogen peroxide.
Explain why the mass of the conical flask and its contents decreased during the reaction.
The graph below shows the results of this first investigation.
Determine the rate of reaction when the time was 404040 seconds. Give your answer to 2 significant figures. Show your working.
The student repeated the investigation using 50 cm350\text{ cm}^350 cm3 of 1.2 mol/dm31.2\text{ mol/dm}^31.2 mol/dm3 hydrogen peroxide solution with the same mass of catalyst.
Describe two key features of the curve you would expect to see for these new results compared to the original curve.