When an aluminum bar is connected between a hot reservoir at 725 K and a cold reservoir at 310 K, 2.50 kJ of energy is transferred by heat from the hot reservoir to the cold reservoir. In this irreversible process, calculate the change in entropy of (a) the hot reservoir, (b) the cold reservoir, and (c) the Universe, neglecting any change in entropy of the aluminum rod.

A quantity of an ideal gas in an isolated system expanded isothermally and reversibly at 400 K from a volume V1 to a volume V2. During the expansion, the gas absorbs 200 cal of heat from the reservoir in contact with it.Calculate (a) the entropy change of the gas;(b) the entropy change of the reservoir, and(c) the entropy change of the whole system.   units should be in j/k, (0.50, -0.50, 0)

Consider a 50.0 g ice cube placed in a container containing 200 g of water. The water is initially at 25.0*C and the ice cube comes directly from a freezer at -15.0*C. Assume no heat is lost to the surroundings and negligible heat loss from the container. Determine the total change in entropy as a result of the mixing process.

A rigid box contains 0.9 mol of an ideal monoatomic gas. Heat is added to the gas and its temperature changes from 183 K to 295 K. If this is a reversible process, what is the change in entropy of the gas in J/K?