Question

When AgNO₃ is dissolved in water, the solution becomes colder. Choose the situation below that best describes this change.

when |Δ_soluteH| > |Δ_hydrationH|

when |Δ_solventH| > |Δ_soluteH|

when |Δ_soluteH| is close to |Δ_hydrationH|

when |Δ_soluteH| < |Δ_hydrationH|

There isn't enough information to determine the answer.

Answer 1

When a solid is dissolved in water, two types of energy changes are involved:

• The energy required to break bonds between solute particles, ∆soluteH(+ve) and
• Energy released as a result of bond formation between solute and solvent molecules, called ∆hydrationH(-ve).

Therefore, the overall ∆H = ∆soluteH + ∆hydrationH

If the overall dissolution is endothermic (because the solution gets colder), ∆H > 0 which means

|∆soluteH| > |∆hydrationH|.

So first option is the correct choice.