Question

Setting of cement is
A.Exothermic reaction
B.Endothermic reaction
C.Neither endothermic nor exothermic
D.None of the above

Answer 1

To answer this question, you should recall the concept of endothermic reactions and exothermic reactions. Endothermic reactions usually involve the formation of chemical bonds via the absorption of heat from the surroundings. Exothermic reactions involve the evolution of heat. The components of cement will determine the type of reaction that will take place.

Complete step by step answer:
Components of cement include a chemical combination of calcium, silicon, aluminum, iron and other ingredients. When water is mixed with cement to form a paste, the reaction starts. In its pure form, the finely ground cement is extremely sensitive to water. It is due to hydration of the molecules of the constituents: dicalcium silicate, tricalcium silicate, tricalcium aluminate. Also, those hydration reactions are exothermic, thus, hydration of the above components and their rearrangements generates heat. This change from a fluid state to a solid-state is called setting. The reactions that cause setting and hardening are collectively described as exothermic hydration reactions. Hence, heat is liberated as the water reacts with the cement during the setting so it’s an exothermic process.

Therefore, it can be concluded that the correct answer to this question is option A.

Additional information: Cement plays a key, but often unnoticed, role in our lives. Cement is mainly used as a binder in concrete, which is a basic material for all types of construction, including housing, roads, schools, hospitals, dams and ports, as well as for decorative applications and items like tables, sculptures or bookcases.

Note: The setting of cement involves hydration reaction. Mostly, hydration reactions are exothermic in nature and thus, setting of cement is also regarded as an exothermic process.