1.1. CFCs were initially introduced in the 1930s by the American engineer Midgley for use in refrigerators. They were especially popular due to their non-toxicity and non-flammability. However, later research showed that CFCs were involved in the depletion of the ozone layer as they release radicals in the upper atmosphere.

An example of a CFC is chlorotrifluoromethane.

i) Explain the importance of ozone.

[1]

ii) Write two equations to show how the radicals decompose the ozone layer and use these to explain why the radicals act as a catalyst in the decomposition of ozone.

[3]

1.2. Due to their damaging effect on the ozone layer, chemists have now developed alternative compounds to CFCs which can be used as solvents and refrigerants. 

An example of such a compound is shown below.

i) State the IUPAC name for the compound shown in and draw its skeletal formula. 

[2]

ii) Explain why the compound shown does not lead to the depletion of the ozone in the upper atmosphere. 

1.3. Bromotrifluoromethane is another halogenated organic compound which is used in fire extinguishers in aircrafts.

The overall equation for the formation of bromotrifluoromethane from trifluoromethane is as follows:

CHF₃ + Br₂ → CBrF₃ + HBr

i) State the type of reaction that occurs when bromine is reacted with trifluoromethane and state one condition required for the first step of this reaction to occur.

[2]

ii) Write an equation for each of the following steps in the mechanism for this reaction.

[4]

1.4. The bond enthalpies of some carbon-halogen bonds are shown in the table below:

Explain, using the data in the table above, whether the environmental impact of CBrF₃ on the ozone layer is more or less severe than that of CClF₃.