Relationship To Heat
In order to discuss the relation between the enthalpy increase and heat supply we return to the first law for closed systems: dU = δQ - δW. We apply it to the special case that the pressure at the surface is uniform. In this case the work term can be split in two contributions, the so-called pV work, given by -pdV (where here p is the pressure at the surface, dV is the increase of the volume of the system) and other types of work δW ' such as by a shaft or by electromagnetic interaction. So we write δW = -pdV+δW '. In this case the first law reads
or
From this relation we see that the increase in enthalpy of a system is equal to the added heat
provided that the system is under constant pressure (dp = 0) and that the only work done by the system is expansion work (δW ' = 0)
Read more about this topic: Enthalpy
Famous quotes containing the words relationship to, relationship and/or heat:
“... the Wall became a magnet for citizens of every generation, class, race, and relationship to the war perhaps because it is the only great public monument that allows the anesthetized holes in the heart to fill with a truly national grief.”
—Adrienne Rich (b. 1929)
“I began to expand my personal service in the church, and to search more diligently for a closer relationship with God among my different business, professional and political interests.”
—Jimmy Carter (James Earl Carter, Jr.)
“The train was crammed, the heat stifling. We feel out of sorts, but do not quite know if we are hungry or drowsy. But when we have fed and slept, life will regain its looks, and the American instruments will make music in the merry cafe described by our friend Lange. And then, sometime later, we die.”
—Vladimir Nabokov (1899–1977)