Which of the following would increase the rate of dissolution of a solid in a solution? 1) Cool the solid and the solution 2) Cool only the solid 3) Dry up the solvent 4) Stir the solid and solution
The Correct Answer and Explanation is :
The correct answer is 4) Stir the solid and solution.
Explanation:
The rate of dissolution of a solid in a solution depends on several factors, including temperature, surface area of the solid, the nature of the solvent, and agitation. Let’s analyze each option:
- Cool the solid and the solution:
Cooling generally decreases the rate of dissolution. This is because dissolution is typically an endothermic process (it requires heat to break the solid into individual particles and incorporate them into the solution). When both the solid and solvent are cooled, the molecules in the solution move more slowly, reducing the energy available for the dissolution process, thereby slowing it down. - Cool only the solid:
Cooling only the solid has a similar effect on the dissolution rate. By cooling the solid, the kinetic energy of the solid’s particles decreases, making it harder for the solid to break apart and dissolve into the solvent. The cooler solid particles will move more slowly, resulting in a reduced dissolution rate. - Dry up the solvent:
Drying up the solvent, meaning reducing the amount of solvent available for dissolution, would slow down the process. A smaller solvent volume means there is less capacity to dissolve the solid, ultimately leading to a slower dissolution rate. Therefore, this would not increase the rate of dissolution. - Stir the solid and solution:
Stirring the solution increases the rate of dissolution. This is because stirring helps to distribute the dissolved particles more evenly throughout the solvent, reducing the concentration of solute near the solid surface. As a result, fresh solvent is constantly brought into contact with the solid, enhancing the dissolution process. Stirring also prevents the formation of a concentrated “layer” of solute around the solid that could impede further dissolution.
In conclusion, stirring the solid and solution promotes the continuous breakdown of the solid into smaller particles, increasing the rate at which the solid dissolves.