Which statement describes the standard enthalpy change of solution when dissolving to form an infinitely dilute solution?

Which statement describes the standard enthalpy change of solution when dissolving to form an infinitely dilute solution?

• A. The enthalpy change when one mole of solute is dissolved in solvent to form an infinitely dilute solution under standard conditions.
• B. The enthalpy change when one mole of solute is dissolved in solvent to form a concentrated solution.
• C. The enthalpy change when solute is dissolved to form a saturated solution.
• D. The enthalpy change when one mole of solute is formed from solvent.

Answer: (A)

The standard enthalpy change of solution is the energy change when one mole of solute dissolves in a solvent to form a solution that is infinitely dilute, measured under standard conditions. This means the amount of solute is so small that solute–solute interactions are negligible and only solute–solvent interactions contribute to the enthalpy change. That exact description—one mole dissolving to give an infinitely dilute solution under standard conditions—is why this option is correct. The other scenarios refer to dissolving to form a concentrated or saturated solution, or to processes like forming a compound from solvent, which do not define the standard enthalpy of solution.

The standard enthalpy change of solution is the energy change when one mole of solute dissolves in a solvent to form a solution that is infinitely dilute, measured under standard conditions. This means the amount of solute is so small that solute–solute interactions are negligible and only solute–solvent interactions contribute to the enthalpy change. That exact description—one mole dissolving to give an infinitely dilute solution under standard conditions—is why this option is correct. The other scenarios refer to dissolving to form a concentrated or saturated solution, or to processes like forming a compound from solvent, which do not define the standard enthalpy of solution.