Science / Chemistry / Enthalpy: Enthalpy (H) is defined so that changes in enthalpy (deltah) are equal to the heat absorbed or released by a process running at constant pressure. While changes in enthalpy can be measured using calorimetry, absolute values of enthalpy usually cannot be determined. Enthalpy is formally defined as H = U + PV, where U is the internal energy, P is the pressure, and V is the volume.
Science / Chemistry / Average Bond Enthalpy: Average enthalpy change per mole when the same type of bond is broken in the gas phase for many similar substances. MORE
Science / Chemistry / Enthalpy Of Fusion: The change in enthalpy when one mole of solid melts to form one mole of liquid. Enthalpies of fusion are always positive because melting involves overcoming some of the intermolecular attractions in t MORE