Describe the flow of energy shown in your sketch of the water and ammonium chloride system.

In a water and ammonium chloride system, the flow of energy can be described as follows:

1. Dissolution of Ammonium Chloride: When ammonium chloride (NH₄Cl) is added to water, the solid salt dissolves, separating into its constituent ions, NH₄⁺ and Cl⁻. This process requires energy, known as the lattice energy, to overcome the forces holding the ions together in the solid state.

2. Energy Transfer: The energy needed for the dissolution comes from the surrounding water. As the ammonium chloride dissolves, it absorbs thermal energy (heat) from the water, resulting in a decrease in the water's temperature.

3. Endothermic Reaction: The dissolution of ammonium chloride in water is an endothermic process, meaning it absorbs heat. This leads to a flow of energy from the water to the ammonium chloride, causing the water to feel cooler.

4. Thermodynamic Considerations: The overall energy change can be affected by factors such as temperature and concentration. In a closed system, the total energy is conserved, but energy can flow between the substances (in this case, from water to the dissolving salt).

5. Equilibrium: Eventually, if the amount of ammonium chloride is sufficient, the dynamic equilibrium will be reached where the rate of dissolution equals the rate of crystallization, and there will be a consistent temperature and distribution of ions in the solution.

In summary, the flow of energy in the water and ammonium chloride system primarily involves the absorption of heat from the water by the dissolving ammonium chloride, resulting in a cooling effect.