A supersaturated solution of sodium thiosulfate is used as a hand warmer. Squeezing a seed crystal of solid sodium thiosulfate into the supersaturated solution causes precipitation of excess solute and the release of heat because:
A) the enthalpy of solution is negative, and solvation is an exothermic process
B) the enthalpy of solution is positive, and solvation is an exothermic process
C) the enthalpy of solution is negative, and solvation is an endothermic process
D) the enthalpy of solution is positive, and solvation is an endothermic process
I would think that the answer was A, because the reaction is releasing heat. Can anyone clarify on how to arrive at the correct answer?
Answer key states D: For a supersaturated solution, equilibrium is reached by precipitation of the excess dissolved solute, and heat is given off when the solute falls out of solution. From this, we conclude that heat must have been absorbed during solvation.
A) the enthalpy of solution is negative, and solvation is an exothermic process
B) the enthalpy of solution is positive, and solvation is an exothermic process
C) the enthalpy of solution is negative, and solvation is an endothermic process
D) the enthalpy of solution is positive, and solvation is an endothermic process
I would think that the answer was A, because the reaction is releasing heat. Can anyone clarify on how to arrive at the correct answer?
Answer key states D: For a supersaturated solution, equilibrium is reached by precipitation of the excess dissolved solute, and heat is given off when the solute falls out of solution. From this, we conclude that heat must have been absorbed during solvation.
