5. 3.4 kg of water is heated from 78 C to boiling and it is all turned to steam at

100C. How much heat did it take?

7.7 MJ

Explanation:

Let water specific heat be c = 0.004186 J/kgC and specific latent heat of vaporization be L = 2264705 J/kg

There would be 2 kinds of heat to achieve this:

- Heat to change water temperature from 78C to boiling point:

- Heat to turn liquid water into steam:

or 7.7 MJ

So the total heat it would take is

explanation:

an enlarged virtual image is the answer