A chemistry student investigates two dissolution processes carried out at 298 K

CHEMISTRY · Multi-part · A Level · Chemistry · Thermodynamics · Thermodynamics

Problem

A chemistry student investigates two dissolution processes carried out at 298 K. Process A:

\mathrm{NH_4Cl(s)} \rightarrow \mathrm{NH_4^+(aq)} + \mathrm{Cl^-(aq)}

Process B:

\mathrm{CaCO_3(s)} \rightarrow \mathrm{Ca^{2+}(aq)} + \mathrm{CO_3^{2-}(aq)}

(1) (a) Predict and justify the sign of

\Delta S^\circ

for Process A. (2) (a) Predict and justify the sign of

\Delta S^\circ

for Process B. (3) (b) Identify which process should exhibit the larger

|\Delta S^\circ|

and justify your choice. (4) (c) Explain qualitatively how powdering the solids before dissolution would affect the sign and relative magnitude of

\Delta S^\circ

for each process.