Physical Chemistry

Write a balanced chemical equation (using state symbols) for the thermal decomposition of ammonium chloride.

Explain, in terms of energy change and temperature, whether this decomposition is endothermic or exothermic. Include what you would expect to observe if touching the outside of the test tube during the reaction.

The student seals the test tube and heats it until no more solid disappears. After some time, the temperature is kept constant. Explain, in terms of reversible reactions and dynamic equilibrium, what happens inside the sealed test tube.

List all the substances present in the reaction mixture at equilibrium in the sealed test tube, and explain your answer.

If the student lowers the temperature of the sealed test tube while it is at equilibrium, predict how the position of equilibrium will shift and what visible change, if any, the student might observe. Explain your answer.