Question

A student has a beaker containing 55g of water at 100°c. how much heat is needed to convert the water to steam

Answer 1

Answer is: 124135 J.
m(water) = 55g.
T(water) = 100°C.
Q = ?
Q - heat needed to convert water to steam.
∆Hvap = 2257 J/g
∆Hvap - enthalpy of vaporization is the amount of energy  needed to transform the liquid substance into a gas.
Q = ∆Hvap · m(water) = 2257 J/g · 55g = 124135 J.

Answer 2

In this case, the water is at 100Degrees and standard pressure so we are already at the boiling point.
 So we only have to do the change phase.
 Heat of vaporization for water (GOOGLE) 2260 J/g.
 So, 55*2260=124300 J.