Which factor influences both solubility and the rate of dissolution?
A. pressure
B. temperature
C. particle size
D. nature of solvent
The Correct Answer and Explanation is:
Correct Answer: B. Temperature
Explanation:
Temperature significantly influences both the solubility of a substance and its rate of dissolution. Here’s why:
1. Solubility
Solubility refers to the maximum amount of solute that can dissolve in a given quantity of solvent at a specific temperature and pressure. Temperature can either increase or decrease the solubility depending on the nature of the solute:
- Endothermic Processes: For many solid solutes, dissolution is endothermic (requires heat). Increasing the temperature provides more thermal energy, which facilitates the breaking of intermolecular forces, allowing more solute to dissolve. For example, sugar and salt dissolve more readily in hot water than in cold water.
- Exothermic Processes: For some substances, like gases dissolving in liquids, solubility decreases with increasing temperature because heat drives the gas molecules out of the liquid.
2. Rate of Dissolution
Rate of dissolution refers to how quickly a solute dissolves in a solvent. Temperature directly impacts this process by:
- Increasing Molecular Kinetic Energy: At higher temperatures, solvent molecules move faster, colliding more frequently and energetically with the solute particles. This accelerates the breaking of bonds in the solute and its integration into the solvent.
- Enhancing Diffusion: The diffusion rate of dissolved particles increases with temperature, speeding up the overall dissolution process.
Why Not the Other Options?
- Pressure (A): Primarily affects the solubility of gases but has little influence on the dissolution rate of solids.
- Particle Size (C): Affects only the rate of dissolution, not solubility. Smaller particles dissolve faster due to increased surface area but do not change how much solute can dissolve.
- Nature of Solvent (D): Impacts solubility by determining compatibility with the solute but does not directly affect the rate of dissolution.
Thus, temperature is the key factor influencing both solubility and the rate of dissolution.