When a system is heated, the rise in temperature depends on three things: the mass of the substance heated, the type of material, and the energy input to the system. More mass or a smaller energy input means a smaller temperature rise. Different materials also warm up by different amounts for the same energy.
The specific heat capacity of a substance is the amount of energy needed to raise the temperature of one kilogram of the substance by one degree Celsius. Water has a high specific heat capacity of 4200 J/kg °C, so it takes a lot of energy to warm it up. A metal such as copper has a much lower value, so it warms up quickly.
The change in thermal energy is found using the equation: change in thermal energy = mass × specific heat capacity × temperature change, or ΔE = m c Δθ. The energy is in joules (J), the mass in kilograms (kg), the specific heat capacity in J/kg °C and the temperature change in °C.
Worked example: 0.50 kg of water is heated from 20 °C to 40 °C. The temperature change is 20 °C. ΔE = 0.50 × 4200 × 20 = 42000 J. Remember to convert grams to kilograms before you substitute.