Final answer:
Solvent extraction can be either an endothermic or exothermic process, depending on the enthalpy changes during the formation of a solution. The process is exothermic if energy released in solvation exceeds the energy absorbed during solvent and solute separation. It is endothermic if the opposite occurs.
Step-by-step explanation:
Solvent extraction is a process that can be either endothermic or exothermic. These terms refer to whether a process absorbs energy (endothermic) or releases energy (exothermic). The enthalpy changes in the formation of a solution involve three steps. Firstly, there's the separation of solvent particles which is endothermic (AH₁ > 0). Secondly, there's the separation of solute particles which is also endothermic (AH₂ > 0). Lastly, in solvation, when solute and solvent interact, energy is released which is exothermic (AH₃ < 0). If the energy released during solvation (AH₃) is greater than the energy absorbed in the first two steps (AH₁ + AH₂), the overall process is exothermic. Otherwise, if the energy released is less, the process is endothermic.
To directly answer the question: Solvent extraction is a process that can be classified as either endothermic or exothermic depending on the relative magnitudes of the enthalpy changes involved in the solution formation.