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:
“Women, because of their colonial relationship to men, have to fight for their own independence. This fight for our own independence will lead to the growth and development of the revolutionary movement in this country. Only the independent woman can be truly effective in the larger revolutionary struggle.”
—Women’s Liberation Workshop, Students for a Democratic Society, Radical political/social activist organization. “Liberation of Women,” in New Left Notes (July 10, 1967)
“Film music should have the same relationship to the film drama that somebody’s piano playing in my living room has to the book I am reading.”
—Igor Stravinsky (1882–1971)
“Glories, like glow-worms, afar off shine bright,
But looked to near, have neither heat nor light.”
—John Webster (1580–1625)