The opposite of the statement in choice B is true: the more highly ordered a system, the lower
its entropy. Choices A and C are statements of the second and third laws of thermodynamics,
respectively. Choice D is correct because if a system is at equilibrium, it is not getting more or
less disordered and thus there should be no change in its entropy.8 . B
This problem uses the concept of conservation of energy. When the metal is put in the water, it
will lose heat; that heat will be transferred to the water. Thus, the amount of heat released by
the metal is the same as the amount of heat absorbed by the water. Use the following
equation for heat transfer:
q = mcΔT
In addition, given a long enough time, the metal and the water will reach thermal equilibrium:
they will eventually have the same temperature. The expressions for the heat released and
absorbed by the metal and water, respectively, are:However, since q should be the same for both equations, the expression can be rewritten:Canceling the 50 g from each side and solving for Tf, which is the final temperature,9 . A
The maximum amount of work that can be done by a spontaneous reaction is the absolute
value of its Gibbs free energy change, and the following equation can be used to solve for it: