OCR A Jan 2012 Paper 2 Q7

Answers available below

7 Chlorofluorocarbons, CFCs, were once used as propellants in aerosols. CFCs contribute to ozone depletion in the upper atmosphere. 18 (a) A CFC has the formula CF2Cl2. State the three-dimensional shape of a CF2Cl2 molecule and the FCCl bond angle. shapebond angle[2] (b) Two reasons that CF2Cl2 was used as an aerosol propellant are that it has low reactivity and will not hydrolyse in water. (i) State one other reason why CF2Cl2 was developed for use as an aerosol.[1] (ii) Suggest why CF2Cl2 does not hydrolyse in water.[1] (c) Explain, with the aid of equations, how the presence of CFCs in the upper atmosphere leads to ozone depletion.[3] (d) Why are scientists concerned about ozone depletion?[1]OCR 2012<br />
 (e) International agreements have reduced the use of CFCs. However the concentration of atmospheric CFCs has hardly changed. 19 Suggest two reasons why.[2] [Total: 10]OCR 2012 Turn over<br />

Show answer