4.6 Entropy

Is it possible for a system to have an entropy change if it neither absorbs nor emits heat during a reversible transition? What happens if the process is irreversible?

Two hundred joules of heat are removed from a heat reservoir at a temperature of 200 K. What is the entropy change of the reservoir?

An ideal gas at 300 K is compressed isothermally to one-fifth its original volume. Determine the entropy change per mole of the gas.

A metal rod is used to conduct heat between two reservoirs at temperatures $T_{\text{h}} \text{and} T_{\text{c}} ,$ respectively. When an amount of heat Q flows through the rod from the hot to the cold reservoir, what is the net entropy change of the rod, the hot reservoir, the cold reservoir, and the universe?

A 5.0-kg piece of lead at a temperature of $600 °\text{C}$ is placed in a lake whose temperature is $15 °\text{C}$. Determine the entropy change of (a) the lead piece, (b) the lake, and (c) the universe.

An ideal monatomic gas is confined to a rigid container. When heat is added reversibly to the gas, its temperature changes from $T_{1} \text{to} T_{2} .$ (a) How much heat is added? (b) What is the change in entropy of the gas?