Apparatus: Two plastic bottles, measuring cylinder, thermometer, etc
Chemicals: Potassium nitrate, sodium hydroxide, water, etc.
(Sodium hydroxide being corrosive, handle it carefully in presence of teacher.)
Procedure: Take I 00 mL water in each of the two plastic bottles. Plastic being insulator of heat, the dissipation of heat can be prevented. Note the temperature of water in the bottles. Put 5 g potassium nitrate `(KNO_3)` in the bottle and shake well. Note the temperature of the solution formed. Put 5 g sodium hydroxide (NaOH) in the other bottle. Shake the bottle well. Note the temperature.
In the first bottle, the process of dissolution of potassium nitrate took place while in the second bottle, the process of dissolution of sodium hydroxide took place
As per your observation which one is exothermic process and which is an endothermic process?

Explanation

The process of dissolution of `KNO_3` in water is endothermic while the process of dissolution of NaOH in water is exothermic process.