An ionic compound has a very negative \(\Delta H_{\text { soln in water. }}\) (a) Would you expect it to be very soluble or nearly insoluble in water? (b) Which term would you expect to be the largest negative number: \(\Delta H_{\text { solvent }} \Delta H_{\text { solute }}\) or \(\Delta H_{\text { mix }}\) ?

Based on the given information that ΔH_soln is very negative, we can deduce that the overall process of dissolving the ionic compound in water releases a large amount of energy. This suggests that the compound likely forms strong interactions with water molecules, which would lead to a high solubility in water. Answer (a): The ionic compound would be expected to be very soluble in water.

To answer the second question, we need to understand the three enthalpy terms involved in the dissolution process: 1. ΔH_solvent: This is the enthalpy change associated with breaking solvent (water) molecules' interactions to create space for the solute particles. 2. ΔH_solute: This term represents the enthalpy change involved in breaking the interactions between solute particles. 3. ΔH_mix: This term represents the enthalpy change associated with the formation of new solute-solvent interactions in the mixture. Note that ΔH_soln = ΔH_solvent + ΔH_solute + ΔH_mix. Since ΔH_soln is very negative, this implies that the energy gained through the formation of new solute-solvent interactions is significantly greater than the energy required to break the solute and solvent interactions.

Considering the relationship between the enthalpy terms and the solubility of the compound in water, we can deduce that: 1. ΔH_solvent and ΔH_solute should be positive or near zero, as energy is required to break the interactions between solvent and solute particles. 2. ΔH_mix must be very negative, as a large amount of energy is released through the formation of strong solute-solvent interactions, making the overall ΔH_soln very negative. Answer (b): We expect the largest negative number to be ΔH_mix.