Answer:
- The second choice: - Hvap.
Step-by-step explanation:
Condensing steam into liquid water is the reverse process of vaporizing liquid water into steam.
The heat or enthalpy of vaporization, also called latent heat of vaporization, of liquid water is the amount of heat that the water absorbs when changes from liquid state to steam (vapour) at certain pressure and it is a constant at every pressure.
The symbol of the latent heat of vaporization is Hvap or ΔHvap.
Thus, being being condensing the reverse process of vaporization, the heat of condensing will be the same magnitude but in reverse direction, i.e. the heat will be released instead of absorbed, and the engineer will have to use the negative of the latent heat of vaporization: - Hvap or - ΔHvap.