A research team studies the chlorination of methane in the gas phase

CHEMISTRY · Multi-part · A Level · Chemistry · Introduction to organic chemistry · Introduction to organic chemistry

Problem

A research team studies the chlorination of methane in the gas phase. The proposed mechanism, carried out at 400 K in the presence of excess argon, is summarized below. Step 1 Cl2  →hν  2 Cl⋅\mathrm{Cl_2 \; \xrightarrow{h\nu} \; 2\,Cl\cdot} Step 2 Cl⋅  +  CH4  ⟶  HCl  +  CH3⋅\mathrm{Cl\cdot \; + \; CH_4 \; \longrightarrow \; HCl \; + \; CH_3\cdot} Step 3 CH3⋅  +  Cl2  ⟶  CH3Cl  +  Cl⋅\mathrm{CH_3\cdot \; + \; Cl_2 \; \longrightarrow \; CH_3Cl \; + \; Cl\cdot} Step 4 Cl⋅  +  Cl⋅  ⟶  Cl2\mathrm{Cl\cdot \; + \; Cl\cdot \; \longrightarrow \; Cl_2} The reaction vessel is continuously flushed with argon to maintain constant pressure. (a) Write the overall balanced equation predicted by the mechanism. (b) Using a clearly labeled table, classify each of the following species with justification: CH4,  CH3Cl,  Cl2,  Cl⋅,  CH3⋅,  HCl,  Ar\mathrm{CH_4,\; CH_3Cl,\; Cl_2,\; Cl\cdot,\; CH_3\cdot,\; HCl,\; Ar}. (c) Identify which species, if any, would appear in the experimentally observed rate law for the overall reaction and briefly justify your choice based on the classifications from part (b).

Related theory

Browse the problem library