Question

Is dissolving KNOз in water spontaneous at all temperatures studied? Explain?

Is the dissolve of KNOз in water giving off heat or require heat? Explain?

Is ∆S calculated consisting with the expected change for the dissolving of KNOз in water?

If the solubility of KNOз in water would decrease with increasing temperature, how would the values of ∆Ct, ∆H, and ∆S be?

Answer 1

Spontaneous reaction = - Delta G. Delta G is given by Delta G = Delta H - T Delta S Since dissolution of KNO_3 in water will disassociate into free ions, the entropy of the process increases and the process is endothermic. Delta G will be negative at all temperatures. So, dissolving KNO_3 in water is spontaneous at all temperatures. Dissolving KNO_3 in water gives K^+ and NO_3^- ions. Since bond is broken in this process, to break the bond energy is required for which the energy should be absorbed and also because the hydration of ions when crystal dissolves does not provide as much energy as it needs to break the crystalline lattice of KNO_3 So dissolving KNO_3 in water is endothermic process. As mentioned in answer a, the entropy of the system increases which makes Delta S positive for all temperatures. sometimes Delta S is negative because there is a large loss of entropy in the hydration of ions. Delta H_solution = 34.89