Heat Capacity
The specific heat capacity is a measure of the energy needed to heat up 1 kilogram of a material to 1°C (or 1K). This has to happen in a temperature range, where the material doesn't change its state of matter, e.g. where water doesn't boil.
Formula: c = Q / ( m * ΔT )
c = specific heat capacity
Q = induced thermal energy
m = mass
ΔT = temperature difference
J = Joule, °C = degrees centigrade, Celsius, K = kelvin
Material at 25°C, if not stated otherwise:
Temperature change from to °C or K
Time: s,
power: watt
Insert three values at c, Q, m and ΔT, the fourth will be calculated. For c you can choose a certain material (the values are approximate). Instead of ΔT, you can enter start and end temperature and transfer it to ΔT by pressing OK. Enter time or power to find out how long you will need for heating up with a certain number of watts.
An example: to heat up a cup of tea (heat capacity virtually that of water, m = 0.2 kg) from room temperature (20°C) to 95°C (ΔT = 75), with a 500 watts microwave oven you will need 125.4 seconds in theory. Practically it will take a bit longer, because the energy conversion efficiency is never 100%.
The specific heat capacity describes the ability of a substance to store thermal energy, i.e. heat. The higher the value, the more heat can be absorbed and released by a certain amount of this substance. Liquid water has one of the highest heat capacities, only surpassed by the gases hydrogen and helium. This is why bodies of water are such good heat storage devices, cooling or warming up long after the temperature of their surroundings. This ensures that regions by the sea and not far from it have more balanced temperatures over the course of a year. In contrast, regions far from the sea and the equator have a so-called continental climate, with often hot summers and very cold winters.
Metals usually have a very low specific heat capacity, with lead and gold having the lowest. These therefore heat up very quickly and cool down again very quickly.
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