Chemistry 9701/53 — May/June 2021
Cambridge A-Level · Planning, Analysis and Evaluation · worked solutions for every part, with the mark scheme
Topics Planning · Analysis, Conclusions and Evaluation
Hydrogen peroxide decomposes slowly at room temperature to give water and oxygen.
The initial rate of this reaction can be increased by the addition of a metal oxide catalyst.
A student is asked to investigate which metal oxide catalyst is best at increasing the initial rate of this reaction by using a method which involves the collection of oxygen.
The student is provided with the following metal oxides: copper(II) oxide, iron(III) oxide, manganese(IV) oxide, nickel(II) oxide and titanium(IV) oxide.
The student is also provided with an excess volume, of a known concentration, of aqueous hydrogen peroxide and any laboratory equipment needed.
State the independent variable.
State the dependent variable.
State two variables that would need to be controlled.
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Draw a labelled diagram of the assembled apparatus that could be used to carry out these experiments. The apparatus should allow the accurate recording of the oxygen produced.
What measurements need to be recorded during the course of each experiment to allow the initial rate to be determined?
How is the initial rate determined using these measurements?
How can the student ensure that the results are reliable?
Suggest an alternative method to investigate these reactions which does not include the collection of gas.
Once the reaction has finished, how can the student demonstrate that the metal oxide has not been affected by the reaction?
When aqueous hydrogen peroxide is stored there is a small hole in the lid of the bottle.
Suggest why this is necessary.
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