Chemistry 5070 · O Level · Alkanes

Alkanes — practice question

Fig. 3.1 displays the equation for the reaction of methane with chlorine. In Fig. 3.1, methane reacts with chlorine to produce chloromethane and hydrogen chloride. Table 3.1 gives some bond energies.
(a)[1]

State one condition needed for this reaction.

(b)[1]

Explain why this reaction counts as a substitution reaction.

(c)[3]

Show by calculation that the enthalpy change of the reaction of methane with chlorine, $\Delta H$, is $-119\text{ kJ/mol}$.

(d)[3]

Complete the reaction pathway diagram in Fig. 3.2 for the reaction of methane with chlorine. Label the reactants, the products, the enthalpy change of the reaction $\Delta H$ and the activation energy $E_a$.

(e)[1]

Draw a dot-and-cross diagram to show the electronic arrangement in a methane molecule. Show only the outer-shell electrons.

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