When solid ammonium chloride, NH4Cl, is added to excess water, a solution forms and the temperature of the system decreases. In a certain experiment, 0.10 mole of NH4Cl is added to a liter of water in an open glass beaker at 298 K. All the salt dissolves in water and there is a decrease in temperature.

1. Explain how the enthalpy, entropy, and free energy of this system change as the dissolving process proceeds.

2. Of the three parameters, ÄS, ÄH, and ÄG, specified in part 1, which has a sign different from the other two? Explain.

3. If this process were carried out in a plastic foam cup rather than a glass beaker, how would the magnitude of the temperature change of the solution be affected? How would the apparent heat of solution be affected? Explain.

4. How is sign and magnitude of the free energy change for this dissolving process affected by an increase in temperature? Explain.