This question is about the reactions of alkanes - AQA - A-Level Chemistry - Question 1 - 2018 - Paper 2

A suitable catalyst for the catalytic cracking of hexadecane is zeolite or aluminosilicate.

One condition for the process is to operate under slight to moderate pressure.

The equation for the catalytic cracking of hexadecane can be represented as:

$C_{16}H_{34} \rightarrow C_7H_{16} + C_6H_{12} + C_3H_6$

The propagation steps involved can be illustrated as follows:

1. $C_4H_{10} + Cl_2 \rightarrow C_4H_9Cl + HCl$
2. $C_4H_9Cl + Cl_2 \rightarrow C_4H_8Cl_2 + HCl$

The radical produced from the CFC (chlorofluorocarbon) that is responsible for ozone depletion is Cl· (Chlorine radical).

The chlorine radical can propagate the reaction that destroys ozone. The reaction sequence is as follows:

1. The chlorine radical reacts with ozone: $Cl· + O_3 \rightarrow ClO· + O_2$
2. The chlorine monoxide radical can react with another ozone molecule: $ClO· + O \rightarrow Cl· + O_2$

This shows that one chlorine radical can lead to the depletion of multiple ozone molecules through a chain reaction.