Energy raises different materials' temperatures at different rates. Metals quickly become hot after absorbing just a little heat. This is why, for instance, your seat belt's metal buckle feels especially hot on a sunny day. Water, in comparison, absorbs a lot more energy before its temperature rises significantly, so a large pot of water takes a long time to heat. The factor linking a material's energy absorption and temperature rise is its specific heat capacity.
Determine the substance's specific heat capacity. For a list of heat capacities, see "Resources."
Subtract the substance's initial temperature from the temperature you want it to reach. If, for instance, a quantity of water is at 20 degrees Celsius, and you need it to rise to 45 degrees Celsius: 45 - 20 = 25 degrees.
Multiply the temperature difference by the specific heat capacity. With water, whose specific heat capacity equals 4.186 joules per degree: 25 x 4.186 = 104.65.
Multiply the result by the substance's mass, measured in grams. Continuing the example, if the water weighs 5,000g: 104.65 x 5,000 = 523,250. The water needs 523,250 joules for its temperature rise.
- Photo Credit Jupiterimages/Photos.com/Getty Images