Explain water equivalent in simple words with examples.
Water equivalent of a substance is the amount of water that would absorb the same amount of heat as the substance per degree rise in temperature.
Explanation: The quantity of heat that raises the temperature of some substance by some amount, the same quantity of heat that can raise the same temperature of a certain mass of water; the mass of water is then called water equivalent.
The heat absorbed or lost by a substance = water equivalent of the substance × temperature increase or decrease.
For example, if we say the water equivalent of a substance is 20 gm, we understand that the heat that is required to raise the temperature of the substance by 1°C can be used to raise the temperature of 20 gm of water by 1°C.
The heat capacity and water equivalent both are equal to the product of the mass of a substance and specific heat. Thus their numerical values are equal. But the units are different. By heat capacity we mean some amount of heat whereas by water equivalent we mean some mass of water.