Gislason and Craig assume there is no chemical reaction or
phase change in the surroundings. They divide the energy
change of part 1' in the surroundings into mechanical and
thermal contributions. If a portion of E, can be converted
into the lifting or lowering, of a weight in the earth’s
gravitational field, this is a “mechanical” energy change denoted
Ew. Any remaining portion of E, is a “thermal” energy
change denoted Ei
as, = as,-Q + AB,-W (6)
Equation 4 becomes
new = -Z AE,-Q - Z as,”
é |' (7)