Chemistry
1c
Title: Surface area and rate of reaction.
Aim: Describe experiments and the effects of changes in
Materials
surface area of a solid on the rate of a reaction. Explain in
terms of particle collision theory.
1 M HCl
Large pieces of
marble chip.
3 beakers.
Pestle and mortar.
Watch glasses
Method:
1. Obtain 3 large marble chips (CaCO3) of approximately the
same size.
2. Measure 25cm3 of 1 mol dm-3 hydrochloric acid into a
small beaker.
3. Add the first marble chip and observe the rate at which
bubbles of carbon dioxide are produced. Cover beaker
with watch glass.
4. Use a pestle and mortar to crush the second marble chip
into small pieces and add this to a fresh 25cm3 sample of
HCl. Note down the rate of production of CO2.
5. Crush the third marble chip completely into a powder.
Add this to the same volume of HCl and observe the rate
of reaction by timing the duration of the reaction.
Safety.
Goggles.
HCl is corrosive at
this concentration.
Possible thinking questions…
1.
2.
3.
4.
5.
6.
7.
Explain why this experiment was a fair test?
Give a word equation for the reaction.
When is the reaction fastest, at the start or the end?
Why does the rate decrease during a chemical reaction?
What happens to the rate of reaction when the marble chips are ground into a powder?
What happens to the surface area when the marble chips are ground into a powder
On the axis below, sketch graphs to show how the rates of reaction will differ when the
marble chips are ground into a powder. Label each curve on the graph.
Volume of CO2
Time
8. Explain in terms of colliding particles, why changing the particle size affects the rate of
reaction. You should included diagrams in your answer.