Controlling reactions

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Question 18
Easy

A student investigates how the surface area of a solid manganese(IV) oxide catalyst, MnO2(s)\text{MnO}_2(\text{s})MnO2​(s), affects the rate of decomposition of hydrogen peroxide, H2O2(aq)\text{H}_2\text{O}_2(\text{aq})H2​O2​(aq):

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}) 2H2​O2​(aq)→2H2​O(l)+O2​(g)

The student compares different physical forms of the catalyst (powder, granules, and large lumps) and measures the volume of oxygen gas produced in the first 60 s of the reaction using the apparatus shown below.

Gas syringe experimental setup measuring the volume of gas released during the decomposition of hydrogen peroxide.

Which two variables must the student keep constant to ensure a fair test?

temperature, mass of MnO2\text{MnO}_2MnO2​ catalyst

volume of oxygen gas collected, concentration of H2O2\text{H}_2\text{O}_2H2​O2​

particle size of MnO2\text{MnO}_2MnO2​ catalyst, temperature

concentration of H2O2\text{H}_2\text{O}_2H2​O2​, volume of oxygen gas collected

Controlling reactions Questions

  1. GCSE
  2. /Chemistry
  3. /Controlling reactions