The amount of heat it takes to increase the temperature of a substance by a given amount depends on whether the heating
is done under conditions of constant volume or constant pressure. The heat added to a system at constant pressure is called
the Enthalpy, ∆H, increase. Changes in enthalpy are directly related to changes in temperature by ∆H=m Cp ∆T
where m is the mass of the substance heated (in grams), Cp is the gram heat capacity at constant pressure (in joules per gram per degree Celsius), and ∆T is the temperature change. We will consistently define ∆T as the final temperature minus the initial temperature, ∆T= Tf -Ti Therefore the temperature change will be negative if Tf