For which one of the following reactions, the entropy change is positive?

Question

For which one of the following reactions, the entropy change is positive? (A) H 2(g)+(1/2) O 2(g) longrightarrow H 2 O (l) (B) Na +(g)+ Cl -(g) longrightarrow NaCl ( s ) (C) NaCl (l) longrightarrow NaCl ( s ) (D) H 2 O (l) longrightarrow H 2 O (g)

Tardigrade Admin · Accepted Answer

Evaporation of water in an open vessel is a process which takes place by itself, by absorption of heat from the surroundings, because the gaseous water molecules are more random than the liquid water molecules.

H_{2} O (l) ⟶ H_{2} O (g); Δ H = + 40.8 k J m o l^{- 1}

In other words, the process is spontaneous because it is accompanied by increase of entropy, which is further a measure of randomness or disorder of the system.

Q. For which one of the following reactions, the entropy change is positive?

$H_{2} (g) + \frac{1}{2} O_{2} (g) ⟶ H_{2} O (l)$

$N a^{+} (g) + C l^{-} (g) ⟶ N a Cl (s)$

$N a Cl (l) ⟶ N a Cl (s)$

$H_{2} O (l) ⟶ H_{2} O (g)$

Q. For which one of the following reactions, the entropy change is positive?

H2​(g)+21​O2​(g)⟶H2​O(l)

Na+(g)+Cl−(g)⟶NaCl(s)

NaCl(l)⟶NaCl(s)

H2​O(l)⟶H2​O(g)

$H_{2} (g) + \frac{1}{2} O_{2} (g) ⟶ H_{2} O (l)$

$N a^{+} (g) + C l^{-} (g) ⟶ N a Cl (s)$

$N a Cl (l) ⟶ N a Cl (s)$

$H_{2} O (l) ⟶ H_{2} O (g)$