Question

Predict the sign of entropy change in following: $2SO_{2}(g)+O_{2}(g) \rightleftharpoons 2SO_{3}(g)$

Answer 1

"Entropy is a "measure" of the lack of thermal energy of any mechanical work system. It also represents the system's randomness. As randomness increases the system entropy. Entropy of the system is directly proportional to the randomness.

Let's predict the sign of entropy change in the following.

$2SO_{ 2 }(g)\quad +\quad O_{ 2 }(g)\quad \rightleftharpoons \quad 2SO_{ 3 }(g)$

There are 3 moles of two different gaseous reactants which have greater randomness than 2 moles of the only gaseous product, ${ SO }_{ 3 }$. Hence, randomness decreases, i.e., $\Delta S\quad is\quad -ve$."