Question
Ethane reacts with chlorine in the presence of sunlight.
Complete the overall equation for this reaction by stating the products.
\({{\text{C}}_{\text{2}}}{{\text{H}}_{\text{6}}} + {\text{C}}{{\text{l}}_{\text{2}}} \to \)
State the type of mechanism by which this reaction occurs.
Traces of butane, \({{\text{C}}_{\text{4}}}{{\text{H}}_{{\text{10}}}}\), are also found amongst the products of this reaction. Explain how this product arises.
Answer/Explanation
Markscheme
\({{\text{C}}_{\text{2}}}{{\text{H}}_{\text{5}}}{\text{Cl}}\) and HCl;
(free) radical substitution / \({{\text{S}}_{\text{R}}}\);
Accept homolytic fission / initiation and propagation (and termination).
ethyl radicals/\({{\text{C}}_{\text{2}}}{{\text{H}}_{\text{5}}} \bullet \) produced;
Accept C2H5.
combine to form butane/\({{\text{C}}_{\text{4}}}{{\text{H}}_{{\text{10}}}}\);
Award [2] for the terminating step equation C2H5\( \bullet + \) C2H5\( \bullet \to \) C4H10.
Examiners report
The reaction of ethane reacting with chlorine in presence of sunlight was well answered although many candidates in part (a) wrote hydrogen as the product. In part (b) the candidates missed the word substitution or free radical instead of the complete answer free radical substitution. In part (c), several candidates mixed up the idea of ethyl free radicals with ethane molecules.
The reaction of ethane reacting with chlorine in presence of sunlight was well answered although many candidates in part (a) wrote hydrogen as the product. In part (b) the candidates missed the word substitution or free radical instead of the complete answer free radical substitution. In part (c), several candidates mixed up the idea of ethyl free radicals with ethane molecules.
The reaction of ethane reacting with chlorine in presence of sunlight was well answered although many candidates in part (a) wrote hydrogen as the product. In part (b) the candidates missed the word substitution or free radical instead of the complete answer free radical substitution. In part (c), several candidates mixed up the idea of ethyl free radicals with ethane molecules.