Final answer:
Dissolving 40g of NH4CL in 100g of water at 50°C leads to a saturated or unsaturated aqueous solution, dependent on the solubility which is not provided. The dissolution of NH4Cl is endothermic, with a negative ΔG, positive ΔH, and positive ΔS.
Step-by-step explanation:
When 40g of NH4CL is dissolved in 100g of water at 50°C, the type of solution formed is a saturated or unsaturated solution. This depends on the solubility of NH4Cl at that temperature since the terminology dictates whether the maximum amount of solute has been dissolved at a given temperature and solvent amount. Ammonium chloride is known to be endothermic when dissolving; thus the temperature of the solution decreases, as observed when it feels cold to touch. To determine whether the solution is saturated or unsaturated without the solubility data at hand, assumptions cannot be made confidently.
Regarding the thermodynamic properties without doing any calculations, the solubility of NH4Cl can give us some clues. Since the process is spontaneous, we know the Gibbs free energy change (ΔG) is negative. The solution feeling cold suggests that the enthalpy change (ΔH) is positive, because the system absorbs heat from the surroundings. For the entropy change (ΔS), when a solid dissolves in water, disorder increases as ions move freely in solution, so ΔS is positive.