The energy needed to change the temperature of a material depends on three things: its mass, its specific heat capacity and the change in temperature. The equation is:
change in thermal energy (J) = mass (kg) × specific heat capacity (J/kg °C) × change in temperature (°C)
The mass must be in kilograms and the energy is in joules, so convert grams to kilograms first. A bigger mass needs more energy: doubling the mass doubles the energy needed. A material with a higher specific heat capacity also needs more energy.
Example: how much energy heats 2 kg of water by 10 °C? Water has a specific heat capacity of 4200 J/kg °C. Energy = 2 × 4200 × 10 = 84000 J. The equation can be rearranged: specific heat capacity = energy ÷ (mass × change in temperature). For a 0.5 kg aluminium block with a specific heat capacity of 900 J/kg °C, heated by 40 °C, the energy is 0.5 × 900 × 40 = 18000 J.