Question

Equimolar amounts of CH₃Br and CH₃I each undergo substitution reactions in bomb calorimeters where OH^- is the nucleophile. Assume the reaction goes to completion in each case, and ignore any further reactions from the leaving group. In which bomb calorimeter will the temperature change be greater? Why?



Now imagine another three bomb calorimeters containing cyclohex-1-ene. Draw the three possible products from the radical removal of hydrogen from either: 1) a carbon at the 2 site, 2) the 3 site, and 4) the 4 site. Which of these reactions will cause the greatest temperature change? Why?

Answer 1

Q1.

Equimolar amounts of CH3Br and CH3I each undergo substitution reactions in bomb calorimeters where OH- is the nucleophile. Assume the reaction goes to completion in each case, and ignore any further reactions from the leaving group. In which bomb calorimeter will the temperature change be greater? Why?

Substitution reaction --> C-Br bond requires much more energy than C-I bond, therefore, when it is broken, it will release more energy, then C-Br substitution is much more exothermic, i.e. the temperature of the surrounding smust increase

C-Br Temperature > C-I temperature