Question

How much energy is required to convert 100.0g of water at 20.0 degrees C to steam at 100.0 degree C? The heat of vaporization for water is DHvap=40.7 kJ/mol

Answer 1

Specific heat of water is 1 cal/g-C,
so raising the 100g 80oC will take 8000 cal
then figure out how many moles of water you have,
100g/(18g/mole)
and calculate the total heat of vaporization
then put cal in terms of J or J in terms of cal so you can add them.