Alkanes

24. ​​ M/J​​ 2016/P11/Q39

How many moles of hydrogen chloride are formed when one mole of methane reacts with a large​​ excess of chlorine in sunlight?

A​​  ​​ ​​ ​​ ​​ ​​​​ 1 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ ​​ 

B​​  ​​ ​​ ​​ ​​ ​​​​ 2​​  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ 

C​​  ​​ ​​ ​​ ​​ ​​​​ 3 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ ​​ 

D​​  ​​ ​​ ​​ ​​ ​​​​ 4

Answer:​​ D

Explaination

This is about substitution reaction of alkane in which chlorine molecule replace H atom from alkane molecule and occupied that space.

Here are the steps of substitution reaction of alkane,

CH4​​ + Cl2  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ ------------------>  ​​ ​​ ​​ ​​ ​​​​ CH3Cl + HCl  ​​ ​​​​ ( 1 mole of HCl )

CH3Cl + Cl2  ​​ ​​ ​​ ​​ ​​ ​​​​ ------------------->  ​​ ​​ ​​ ​​​​ CH2Cl2​​ + HCl  ​​​​ ( 1 mole of HCl )

CH2Cl2​​ + Cl2  ​​ ​​ ​​ ​​​​ ------------------->  ​​ ​​ ​​ ​​​​ CHCl3​​ + HCl  ​​ ​​​​ ( 1 mole of HCl )

CHCl3​​ + Cl2  ​​ ​​ ​​ ​​ ​​ ​​​​ ------------------->  ​​ ​​ ​​ ​​​​ CCl4​​ + HCl  ​​ ​​ ​​ ​​ ​​​​ ( 1 mole of HCl )

The final summarized equation will be

CH4​​ + 4Cl2  ​​ ​​ ​​ ​​ ​​ ​​​​ -------------------------------------->  ​​ ​​ ​​ ​​ ​​​​ CCl4​​ + 4HCl

So, total 4 moles of HCl are formed.