Enthalpy of vaporization

[Sabrina 1F]

∆HVap= H_m (vapor)−H_m (liquid)
Would someone mind explaining each individual H of the formula? Also what do the little m's mean? (I got the equation from the book)

Thank you!

[Thuy-Anh Bui 1I]

Enthalpy of vaporization (ΔH_vap) is the difference in molar enthalpy (H_m) between the vapor and liquid states. All the "H"s mean enthalpy. The "Δ" in ΔH_vap shows the change in enthalpy of the vapor and liquid states. The "m" in H_m indicates that we are using molar enthalpy. Hope this helps!

[Leah Thomas 2E]

Also, ΔH of vaporization is the change of enthalpy so to explain the equation you have to take the enthalpy of vapor subtracted from the enthalpy of liquid because it references again final-initial. In this case, vapor is the final product.