Question

When pellets of NaOH(s) are added to a flask of water, it is observed that the temperature of the water increases as the pellets dissolve. Which of the following claims about the observed dissolution of NaOH(s) in water is most accurate?
A. It is an endothermic process because heat energy is absorbed by the water as the NaOH(s) dissolves in it.

B. It is an endothermic process because heat energy is released by the water as the NaOH(s) dissolves in it.

C. It is an exothermic process because heat energy is absorbed by the water as the NaOH(s) dissolves in it.

D. It is an exothermic process because heat energy is released by the water as the NaOH(s)) dissolves in it.

Answer 1

Answer: It is an exothermic process because heat energy is absorbed by the water as the NaOH(s) dissolves in it.

Explanation:

Endothermic reaction : It is a type of chemical reaction where the energy is absorbed from the surrounding. In the endothermic reaction, the reactant are less than the energy of product. In endothermic reaction, the change in enthalpy is, positive

Exothermic reaction : It is a type of chemical reaction where the energy is released into the surrounding. In the exothermic reaction, the energy of reactant are more than the energy of product. In exothermic reaction, the change in enthalpy is, negative.

Thus as energy is absorbed by water, which has been released by NaOH, the process is exothermic.