Question

Predict the sign of entropy change in following: $2NH_{4}NO_{3}(s) \longrightarrow 2N_{2}(g)+4H_{2}O(g)+O_{2}(g)$

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.

In the given chemical reaction "ammonium nitrate" decomposes into nitrogen gas, water, and oxygen gas.

$2NH_{ 4 }NO_{ 3 }(s)\quad \longrightarrow \quad 2N_{ 2 }(g)\quad +\quad 4H_{ 2 }O(g)\quad +\quad O_{ 2 }(g)$

Here, solid is convert into gas phase. The "randomness" is more in gas phase. Therefore, sign of entropy is positive."