Medical College Admission Test (MCAT) Practice Exam

Overcoming intermolecular forces to dissolve a substance is characterized as an endothermic process. This occurs because energy must be supplied to break the attractive forces between the molecules of the solute as well as potentially between the solvent molecules.

When a solute dissolves, the intermolecular interactions within the solute must be overcome, which requires energy. For instance, in the case of salt (NaCl) dissolving in water, the ionic bonds between the sodium and chloride ions need to be disrupted, and this process absorbs energy from the surroundings, leading to a decrease in temperature in some cases.

Even though some dissolving processes can also release energy (for example, hydration energy when ions interact with water), the initial step of breaking the solute's intermolecular forces is always endothermic. Thus, the overall process of dissolving a substance generally requires energy input, confirming its classification as endothermic.