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.

The process can be performed under slight to moderate pressure, typically around 1.5 atmospheres.

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

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

Here, the products are one molecule of heptane, one molecule of cyclohexane (C6H12), and propane (C3H8).

The propagation steps for the formation of 2-chlorobutane from butane can be illustrated as:

1. $C_4H_{10} + Cl \cdot \rightarrow C_4H_9Cl + HCl$

2. $C_4H_9 \cdot + Cl_2 \rightarrow C_4H_9Cl + Cl \cdot$

In these reactions, butane reacts with a chlorine radical to form 2-chlorobutane and regenerate the chlorine radical.

The radical produced from a chlorofluorocarbon (CFC) responsible for ozone depletion is a chlorine radical (Cl \cdot).

A single chlorine radical can catalyze the destruction of multiple ozone molecules through a chain reaction. For example, the reaction begins as follows:

1. $Cl \cdot + O_3 \rightarrow ClO \cdot + O_2$

2. Then, the chlorine monoxide radical can further react with another ozone molecule:

$ClO \cdot + O \rightarrow Cl \cdot + O_2$

In this sequence, the chlorine radical (Cl \cdot) is regenerated and can continue to react with more ozone (O3), leading to the depletion of the ozone layer.