How much heat is needed to heat 5 g of water from 0°C to 100°C?
The amount of heat absorbed by a substance to change its temperature is proportional to the mass of the substance, and the temperature variation, that is to be achieved.
The equation of the amount of heat absorbed or released by a substance, for the variation of its temperature is:
Q = m Ce (Tf – Ti)
Q: is the amount of heat absorbed or released.
Ce: is the specific heat of the substance. This amount represents the amount of heat required to vary to a degree (1°C), the unit of mass of the substance in question.
m: is the mass of the substance.
Ti: is the initial temperature.
Tf: is the final temperature.
In the case of water, the specific heat is:
Ce = 1 cal/°C*g
Substituting in the equation we have:
Q = (5g)(1 cal/°C*g)(100° – 0°)
Q = 500 cal
So to raise the temperature of 5 g of water from 0° to 100°, 500 cal of heat are required.