The scenario that would lead to an endothermic ΔHsolution is when |ΔHsolute| > |ΔHhydration|. Explanation: A solution is characterized as a homogeneous mixture of two or more substances that can exist in gas, liquid, or solid forms. The enthalpy of solution may either be positive (indicating an endothermic reaction) or negative (indicating an exothermic reaction). Enthalpy represents the heat released or absorbed during the dissolution process at constant pressure. The initial step of this process involves separating the solute, which breaks all the intermolecular forces binding the solute together. This separation is an endothermic process, requiring energy to disrupt these interactions. Therefore, ΔH1 is positive. Consequently, for this situation to result in an endothermic reaction, the enthalpy of the solute must exceed the enthalpy of hydration.
Calculation yields 209.53. The molar concentration is calculated by moles divided by volume. Given the volume of 750 mL, which translates to 0.75 L, the moles of CuBr₂ can be determined as molar concentration multiplied by volume, resulting in 1.25 × 0.75 = 0.9375. Mole count is derived from the mass of CuBr₂ divided by its molecular mass. The molecular mass of CuBr₂ is computed as 63.5 + 80 × 2 = 223.5, where the mass of Cu is 63.5 and that of Br is 80. Consequently, the mass needed amounts to 223.5 × 0.9375 = 209.53 g.