Entropy: A system consists of two very large thermal reservoirs in contact with each other, one at temperature 300°C and the other at temperature 200°C. When 600 J of heat transfers from the 300°C reservoir to the 200°C reservoir, what is the change in entropy of this system?
A) 0.221 J/K
B) 1.00 J/K
C) 5.00 J/K
D) -1.00 J/K
E) -2.31 J/K

Question

Quizplus · Accepted Answer

The change in entropy for the system is calculated using the formula ΔS = Q/T. For the reservoir at 300°C (573 K), ΔS1 = -600 J / 573 K = -1.047 J/K. For the reservoir at 200°C (473 K), ΔS2 = 600 J / 473 K = 1.268 J/K. The total change in entropy is ΔS = ΔS1 + ΔS2 = -1.047 J/K + 1.268 J/K = 0.221 J/K.

Entropy: a System Consists of Two Very Large Thermal Reservoirs