Method 1. Place two small marble chips in a conical flask. 2. Add 25 cm3
the flask, acid and marble chips.
3. Put the cotton wool in the neck of the conical flask to stop any acid from splashing out (as shown in Figs. 2 and 3).
4. Record the mass of the flask after 2 minutes.
of hydrochloric acid to the flask and immediately write down the mass of
Fig. 2 Mass at the start of the experiment.
Fig. 3 Mass after 3 minutes.
In the above activity you measured a change in mass over a period of time. By calculating the amount of mass lost per second it is possible to measure the rate of the reaction. Total mass lost Time taken
Rate of reaction =
Extended Investigation Effect of particle size and concentration on rate of reaction Use effervescent tablets or the reaction between hydrochloric acid and marble chips to investigate one of the following: 1. Design an experiment to investigate the effect of particle size on the rate of reaction. 2. Design an experiment to investigate the effect of concentration on the rate of reaction.
Production of oxygen Oxygen occupies about 20% of the air around us. One way that oxygen can be produced in the laboratory is by the breakdown of hydrogen peroxide. Hydrogen peroxide breaks down slowly over time into water and oxygen. This is the balanced equation for the reaction: 2H2
O2 g 2H2 272 O + O2 Hydrogen peroxide g Water + Oxygen
