If the pressure during the reaction stays CONSTANT (but the volume can change, like in a piston or balloon), which of these reactions do work on the surroundings?
A (s) + B (g) --> C (g)
A (g) + B (g) --> C (s)
A (s) + B (aq) --> 2 C (g)
A (g) + B (g) --> 3 C (g)
A (s) + B (g) --> 2 C (g)
A (g) + B (s) --> C (s) + D (g)