Question

Take a glass beaker. Add some water in it. Note the temperature of water with the help of a thermometer. Now add $KN{{O}_{3}}$ powder in it. Shake the beaker well and note down the temperature with a thermometer. What happens when there is a change in temperature?

Answer 1

Hint As a certain amount of potassium nitrate is accumulated in some amount of water, the time substance takes to dissolve is termed as solubility of the salt. There are many factors affecting solubility, such as polarity of the solvent, temperature of the mixture, mass of the solvent, etc.

Complete step by step answer:
- Potassium Nitrate is a crystalline salt and a strong oxidizing agent used especially in making gunpowder, as a fertilizer, and in medicine.
- $KN{{O}_{3}}$ is discreetly soluble in water. Its solubility increases with increase in temperature.
- Since the hydration of the ions when the crystal dissolves does not provide as much energy as is needed to break up the lattice, the process of dissolving potassium nitrate in water is an endothermic process.
- As the randomness of the system increases, the change in entropy ($\Delta S$) for potassium nitrate dissolved in water always stays positive.
- This process being an endothermic reaction, the change in enthalpy ($\Delta H$) would also be positive.

Note: As the temperature of water increases, the particles of solid $KN{{O}_{3}}$, which absorb energy from its surrounding, start moving more easily between the solution and its solid state. After considering the second law of thermodynamics, the particles will shift to the more disordered state hence, more highly dispersed solution state.