Every chemical reaction has a DH value. What does the symbol "DH" mean?
Every chemical reaction is either endothermic (heat absorbing) or exothermic (heat producing.) Capital H in chemistry (not to be confused with the element Hydrogen!!) will be found with reaction formulas and refers to the Heat of Formation, or the amount of thermal energy absorbed or released in the chemical reaction. The change in the Heat of Formation occurs when the reaction proceeds; the concept of the thermal change in the reactants is usually expressed as "Delta" H, or ∆H.