If the mass of a substance is doubled while keeping the temperature change and specific heat capacity the same, what happens to the required heat energy?

• A. It doubles.
• B. It halves.
• C. It quadruples.
• D. It stays the same.

Answer: (A)

The amount of heat needed to raise a substance’s temperature depends on how much material there is, its specific heat, and how big a temperature change you want. This is described by Q = m c ΔT. If the temperature change ΔT and the specific heat capacity c stay the same and you double the mass m, the heat required doubles as well, because the product m c ΔT becomes 2 times larger. So, the energy you need goes from Q to 2Q. More mass means more energy is needed to achieve the same temperature rise.