MYP 10
 
 


Unit 10.6.6: Catalysts

Objectives

  • To know that catalysts are substances that increase the rate of a chemical reaction and which can be recovered chemically unchanged at the end of the reaction
  • To plan and carry out an investigation into catalysis

Introduction

The students are shown the reaction between zinc and sulfuric acid both with and without a catalyst (copper ions).

The nature of catalysis may emerge from the discussion in which case their action may be described as due to either:

  • 1. A template effect (fly-paper, fly and bird) or
  • 2. The formation of an intermediate, which in turn reacts to regenerate the catalyst.

Both of these processes often involve electron transfer (redox) reactions, making transition metals and their compounds good candidates for catalysts.

Student activity

The students are to plan an investigation into the catalytic breakdown of hydrogen peroxide by manganese(IV) oxide.

Provided:

  • Hydrogen peroxide solution (20 vol)
  • Manganese(IV) oxide powder, MnO2

All the usual laboratory apparatus

Assessment

Criterion B

Criterion C

Teaching notes

Hydrogen peroxide concentration is measured in 'volumes'. This refers to the volume of oxygen that a given volume of hydrogen peroxide solution can produce. 100 vol H2O2 makes 100 times its own volume of oxygen:

2H2O2 2H2O + O2

Hydrogen peroxide will bleach the skin and irritate the eyes. Suitable safety precautions must be taken.

Resources

The rates of chemical reactions


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