Chapter 15, Problem 3STP

Interpretation Introduction

Interpretation: The action that does not generally increase the rate of dissolution needs to be explained.

Concept introduction: When a solid is dissolves in a solvent to form a solution, the process of dissolution may happen rapidly or slowly. Factors which affect the rate of the dissolution are (a) surface area (b) stirring, and (c) temperature.

Answer to Problem 3STP

Option “D” is correct option.

Explanation of Solution

Every solvent has maximum limit to dissolve a particular solute at particular temperature. If the solution reaches its saturation point, it can no longer dissolve more solute and excess solute will remain at the bottom of the tube or glass. So, simply addition of solute will not generally increase the rate of dissolution.

Conclusion

Dissolving occurs at the surface of the solute being dissolved. So, larger the surface area exposed to the solvent, the more rapid is the dissolution.

Stirring the solution increases the interaction between solute and solvent and thus increases the solubility.

Upon raising the temperature kinetic energy of the solvent molecule increases which increases the rate collision between solute particles and solvent molecules. Hence, increase of temperature increases the rate of dissolution.

Hence, option A, B and C cannot be the answer.