A sample of methane gas of mass os 15g at 260K and 105kpa expands isothermally and a) reversible, b) irreversible until its pressure is 1.50kpa. calculate the change in entropy of the gases

 

 

 

When an aluminum bar is temporarily connected between a hotreservoir at 800 K and a cold reservoir at 278 K, 2.30 kJ of energyis transferred by heat from the hot reservoir to the coldreservoir.
(a) In this irreversible process, calculate the change in entropyof the hot reservoir.
J/K

(b) In this irreversible process, calculate the change in entropyof the cold reservoir.
J/K

(c) In this irreversible process, calculate the change in entropyof the Universe, neglecting any change in entropy of the aluminumrod.
J/K

(d) Mathematically, why did the result for the Universe in part (c)have to be positive?

When an aluminum bar is temporarily connected between a hotreservoir at 770 K and a cold reservoir at 288 K, 2.10 kJ of energyis transferred by heat from the hot reservoir to the coldreservoir.
(a) In this irreversible process, calculate the change in entropyof the hot reservoir.
J/K

(b) In this irreversible process, calculate the change in entropyof the cold reservoir.
J/K

(c) In this irreversible process, calculate the change in entropyof the Universe, neglecting any change in entropy of the aluminumrod.
J/K

(d) Mathematically, why did the result for the Universe in part (c)have to be positive?