IB Chemistry HL 3.3.3 Radical Substitution Question Bank

Practise IB Chemistry HL 3.3.3 Radical Substitution with focused questions on electron movement, radical steps and reaction products.

[Maximum number: 4]

This question is about carbon and chlorine compounds.

(a)

Ethane, $\mathrm{C}_{2} \mathrm{H}_{6}$ , reacts with chlorine in sunlight. State the type of this reaction and the name of the mechanism by which it occurs.

Type of reaction:

Mechanism:

[ 1 ]

substitution AND «free-»radical

OR

substitution AND chain

Marking guidance:

Award [1] for "«free-»radical substitution" or "S ${ }_{R}$ " written anywhere in the answer.

(b)

Formulate equations for the two propagation steps and one termination step in the formation of chloroethane from ethane.

Two propagation steps:

One termination step:

[ 3 ]

Two propagation steps:
$\mathrm{C}_{2}\mathrm{H}_{6}+\bullet\mathrm{Cl} \rightarrow \mathrm{C}_{2}\mathrm{H}_{5}\bullet+\mathrm{HCl}$ $\mathrm{C}_{2}\mathrm{H}_{5}\bullet+\mathrm{Cl}_{2} \rightarrow \mathrm{C}_{2}\mathrm{H}_{5}\mathrm{Cl}+\bullet\mathrm{Cl}$

One termination step, for example:
$\mathrm{C}_{2}\mathrm{H}_{5}\bullet+\mathrm{C}_{2}\mathrm{H}_{5}\bullet \rightarrow \mathrm{C}_{4}\mathrm{H}_{10}$

or:
$\mathrm{C}_{2}\mathrm{H}_{5}\bullet+\bullet\mathrm{Cl} \rightarrow \mathrm{C}_{2}\mathrm{H}_{5}\mathrm{Cl}$

or:
$\bullet\mathrm{Cl}+\bullet\mathrm{Cl} \rightarrow \mathrm{Cl}_{2}$

All question bank results loaded

3.3.3—Radical substitution question 1

Question (a)

Question (b)