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 a zeolite or aluminosilicate.

The reaction should occur under slight or moderate pressure.

The equation for the catalytic cracking can be represented as:

$C_{16}H_{34} \rightarrow C_7H_{16} + C_6H_{12} + C_3H_8$

The propagation steps are as follows:

1. Formation of a radical: $C_4H_{10} + Cl \rightarrow C_4H_9^* + HCl$

2. Reaction of the butyl radical with chlorine: $C_4H_9^* + Cl_2 \rightarrow C_4H_9Cl + Cl^*$

The radical produced from a CFC that contributes to ozone depletion is the chlorine radical (Cl^*).

A single chlorine radical can initiate a chain reaction for the decomposition of ozone. The process can be summarized as follows:

1. The chlorine radical reacts with ozone: $Cl^* + O_3 \rightarrow ClO^* + O_2$

2. The chlorine monoxide radical then reacts with another ozone molecule: $ClO^* + O_3 \rightarrow Cl^* + 2O_2$

Thus, one chlorine radical can decompose many ozone molecules (O3) in a cyclic manner.