In which of the following processes entropy increases? A. A liquid evaporates to vapour. B. Temperature of a…
In which of the following processes entropy increases?
A. A liquid evaporates to vapour.
B. Temperature of a crystalline solid lowered from 130 K to 0 K .
C. $2 \mathrm{NaHCO}_{3(\mathrm{~s})} \rightarrow \mathrm{Na}_2 \mathrm{CO}_{3(\mathrm{~s})}+\mathrm{CO}_{2(\mathrm{~g})}+\mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}$
D. $\mathrm{Cl}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{Cl}_{(\mathrm{g})}$
Choose the correct answer from the options given below:
A, B and D
A, C and D
C and D
A and C
Solution
When a liquid evaporates to vapour entropy increases
$2 \mathrm{NaHCO}_{3(\mathrm{~s})} \rightarrow \mathrm{Na}_2 \mathrm{CO}_{3(\mathrm{~s})}+\mathrm{CO}_{2(\mathrm{~g})}+\mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}$
Number of gaseous product molecules increases so entropy increases.
$\mathrm{Cl}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{Cl}_{(\mathrm{g})}$
1 mole $\mathrm{Cl}_{2(\mathrm{~g})}$ form $2 \mathrm{~mol} \mathrm{Cl}_{(\mathrm{g})}$. So entropy increases.