- #1

Amin2014

- 113

- 3

vs

##dU = dw + dq + µdN##

Which equation do we apply to a closed system involving chemical reaction? According to textbooks, the first equation holds for any closed system in the absence of fields and kinetic energy. However, later chapters use the second equation for closed systems involving irreversible chemical reactions. This doesn't make sense to me because the first law for surroundings gives:

##dU_{surr}= -dw - dq##

Combined with ##dU = dw + dq + µdN## we have :

## dU_{univ} = dU + dU_{surr} = µdN ## ! Which contradicts the statement that energy is conserved for an isolated system.