Question

For which of the following the entropy change is negative?

• A. Conversion of ozone to oxygen gas
• B. Conversion of graphite to diamond
• C. Both a and b
• D. None of the above

Answer 1

The correct option is B Conversion of graphite to diamond

Considering the options one by one,

a) $2O_3\left(g\right)\to 3O_2\left(g\right)$
As the number of gaseous moles is increasing, $△n_g>0$
where,
$△n_g=n_p-n_R$
$n_P=$ total number of gaseous moles of products
$n_R=$ total number of gaseous moles of reactants
$\Rightarrow △S>0$

b) In the conversion of graphite to diamond, the randomness decreases as diamond has a more organised and packed structure than graphite. So, $\Rightarrow △S<0$