Page 115 - Science Coursebook

8.5 Concentration and the rate of reaction

If you carried out an experiment with marble chips and hydrochloric acid,

using the same size and same mass of chips, the same temperature but different
concentrations of the acid, what would you expect to happen?

Activity 8.5A

Planning an investigation into the effect of concentration

In this experiment you will change the concentration of the
acid used. Instead of measuring the volume of carbon dioxide
produced every 30 seconds, you will use a slightly different method

of measuring the rate of the reaction – timing how long it takes to
3
collect 25 cm of carbon dioxide in the measuring cylinder.

measuring
cylinder

dilute
hydrochloric
acid

marble
chips

timer

Discuss in your group how you will carry out this investigation.
Things to be considered are:

• Which factors will you keep the same?
• What mass of marble chips will you use?
• What volume of acid will you use?
• Which concentrations of acid will you use?
• What safety precautions should you take?
• Do you need to do a trial run or some preliminary work?
• If so what do you want to find out?

• Do you need to repeat any of your readings?
When you have planned your investigation show it to your teacher.

8 Rates of reaction 113