How many kilojoules are required to warm 25.0 g of water from 75.0 C to 100.0 C and convert it to steam at 100.0 C? The heat of vaporization of water is 2260 joules/g, and the the specific heat of water is 4.184 joules/g?
You have to add the energy required for the heating up and the energy for the vapourizing.
To heat 1 gram of water from 75 to 100 deg C means a temperture rise of 25 deg C.
To vapourize that same gram:
So total energy required to heat up and vapourize 1 gram:
Multiply this by the mass of the water:
(rounded to 3 SF)