Which material is noted for absorbing heat due to its moisture content during heating?

• A. Gypsum
• B. Fiberglass
• C. Steel
• D. Concrete

Answer: (A)

When a material contains moisture, heating it causes that moisture to heat up and, if it’s bound water, to be released in a phase-change or dehydration process. This takes in a lot of energy, slowing the rise in temperature. Gypsum plaster is known for this because it contains water of crystallization in its structure. As it is heated, the bound water is driven off in a dehydration reaction, which is endothermic and absorbs a significant amount of heat. This makes gypsum-based materials effective heat absorbers during heating.

Fiberglass doesn’t rely on moisture to absorb heat; it’s primarily an insulator. Steel, being a metal, conducts heat rather than absorbing it via moisture. Concrete does contain moisture in pores, but its heat absorption isn’t dominated by moisture release in the same way as gypsum’s dehydration, which is a more pronounced, moisture-driven heat sink in heating scenarios.