Question

What is the energy change of the system if a chemical reaction transfers 32,146 J of heat to the surroundings while it causes the expansion of a 1.465 liter vessel to 3.687 liters against a pressure of 3.64 atmospheres?

Answer 1

Heat transfer to the surroundings Q = -32146 J

Work done W = P( V ' - V )

                    = (3.64 atm ) (3.687 lit -1.465 lit)

                     = (3.64 x1.01 x10 ⁵ Pa) (2.222 x10 ^-3 m ³ )      Since 2.222 Lit = 2.222x10 ^-3 m ³

                    = 816.89 J

Energy change of the system U = Q - W

                                               = -32146 J -816.89 J

                                               = -32962.89 J