6.25 Water within a piston-cylinder assembly, initially at 10 lbf/in.2, 500°F, undergoes an internally reversible process to 80 lbf/in.2, 800°F, during which the temperature varies linearly with specific entropy. For the water, determine the work and heat transfer, each in Btu/lb. Neglect kinetic and potential energy effects.

How much energy must be transferred as heat for a reversible isothermal expansion of an ideal gas at 132°C if the entropy of the gas increases by 46.0 K

The Sun radiates energy at the rate of 3.80 ✕ 1026 W from its 5500°C surface into dark empty space (a negligible fraction radiates onto Earth and the other planets). The effective temperature of deep space is −270°C. (Due to the sensitive nature of the calculations, use  T(K) = T(°C) + 273.15. ) (a) What is the increase in entropy (in J/K) in one day due to this heat transfer?

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?

A block made of cobalt with a mass of 0.80 kg is heated to 850°C, then dropped into 5.00 kg of water at 10°C. What is the total change in entropy (in J/K) of the block-water system, assuming no energy is lost by heat from this system to the surroundings? The specific heat of cobalt is 420 J/(kg · K), and the specific heat of water is 4,186 J/(kg · K). (Hint: note that dQ = mcdT.)

The temperature of 2.27 kg of air is decreased from 148.9oC to 4.44oC while the pressure is constant. Calculate the change of entropy in kJ/K?

Steam enters a diffuser at 20 psia and 240F with a velocity of 900 ft/s and exits as saturated vapor at 240F and 100 ft/s. The exit area of the diffuser is 1 ft2. Determine (a) the mass flow rate of the steam and (b) the rate of entropy generation during this process. Assume an ambient temperature of 77F.

A 100-lbm block of a solid material whose specific heat is 0.5 Btu/lbm·R is at 80°F. It is heated with 10 lbm of saturated water vapor that has a constant pressure of 20 psia. Determine the final temperature of the block and water, and the entropy change of the entire system. Is this process possible? Why?