(a) Using the BDEs in Table 4-2 (p. 143), compute the

Question

Problem 17P Using the BDEs in Table 4-2 (p. 143), compute the value of $\Delta H^{\circ}$ for each step in the iodination of methane.

Compute the overall value of $\Delta H^{\circ}$ for iodination.

Suggest two reasons why iodine does not react well with methane.

Equation Transcription:

$\Delta{}H$ $°$

Text Transcription:

\Delta H^\circ

Answer 1

Step-by-Step Solution:

Solution:

Step 1

The iodination of methane can be carried out by the following ways:-

I2 + CH3 $\rightarrow{}$ I-CH3 + I .

Mechanism:-

1)Initiation:-

This step involves the generation of active species (free radical)

2) Propagation:-

This process involves the growth of a polymer chain by successive addition of monomers during propagation can be represented as follows:-

The value of ΔH° for each step in the formation of iodination of methane can be calculate as,

For breaking I-I , ΔH° = +151 KJ/mole (+ 36 Kcal/mole)

For breaking H-CH3, ΔH° = +435 KJ/mole (+ 104 Kcal/mole)

For making H-I , ΔH° = -297 KJ/Mole (-71 KCal/mole)

Total ΔH° = +138 KJ/mole (+ 33Kcal/mole)

To break I-I ΔH° = +151 KJ/mole (+36 Kcal/mole)

To make I-CH3 ΔH° = -234 KJ/mole (-56Kcal/mole)

Total ΔH° = -83 KJ/mole (-20 Kcal/mole)

Step 2 of 3

Step 3 of 3

Solution for problem 17P Chapter 4