How much heat in joules is needed to vaporize an 18.0 gram sample of water at 100c?

The water is already at its boiling point , therefore we don't need additional heat to increase its temperature. Instead, we have to give the heat necessary to make it evaporate. The energy needed is equal to

where
m is the mass of the water
Lv is the latent heat of evaporation

The latent heat of evaporation of water is , and the mass of this sample of water is , therefore the heat needed to vaporize the water is