Question

If 200 grams of water is to be heated from 24.0 degrees Celsius to 100.0 degrees Celsius to make a cup of tea, how much heat must be added?

Answer 1

Conveniently, some scientists have already figured out how much heat energy it takes to increase the temperature of one gram of water by exactly 1 degree Celsius. That is called the specific heat of water and it's value is 4.184J/g.

So simply multiply the specific heat with the number of grams and the number of degrees C like this:

$heat = 4.184J/g * 200g * 76^o C = 63,596.8J = 63.5968 kJ$