Question

how does thermal and chemical energy interact in a system made up of water and ammonium chloride

Answer 1

Answer:

There is reaction but it's a series of equilibria we have to consider, not a simple complete change.

First the ions separate:

NH4+Cl-(s) = NH4+(aq) + Cl-(aq)

Ammonia is a weak base and water contains hydroxide ions from its dissociation:

H2O = H+(aq) + OH-(aq)

So some ions react:

NH4+(aq) + OH-(aq) = NH4OH(aq)

This means that more water splits up to replace the lost hydroxide ions. This results in a build up of hydrogen ions and this is why the solution is acidic.