### PHYsics 1151 Chapter 18, Thermodynamics

D18.1 An ideal gas is sealed in a rigid container at 25°C and 1.0 atm. What will its temperature be when the pressure is incresed to 2.0 atm?

What will its pressure be when the temperature is increased to 50°C?

D18.2 Gas at 1.5 atm expands from 2.5 liters to 3.5 liters. How much work is done by the gas?

D18.3 Under a constant pressure of 1.5 atm, a gas expands from 2.0 liters to 3.0 liters while 500 J of energy flows into it.
(a) How much work is done by the gas?
(b) What is the change in its internal energy?

D18.4 Under a constant pressure of 2.25 atm, a gas is compressed from 2.00 l to 1.50 l while 375 J of energy flows out of the gas.

(a) How much work is done on the gas?
(b) What is the change in its internal energy?

D18.5 After 1.0 mol of an ideal gas initially at 0°C and 1.0 atm expands isothermally to twice its initial volume, it is compressed isobarically back to its original volume. What is the net work done by or on the gas? What is its final temperature?
This calls for a p-V diagram.
D18.5 A heat engine absorbs 6 J from a source of heat and does 2 J of mechanical work. What is its efficiency?

D19.6 A reversible heat engine whose efficience is 15 percent does 180 J of work. How much heat does it absorb from the hot reservoir?

D18.7 A Carnot engine operates with a hot reservior of 650°C at 0.30 efficiency. To have 0.35 efficiency, what must the temperature of this erservoir be?

D18.8
The efficiency of a sasoline engine is 0.55. Estimate the temperature of the combustion gases if the exhaust gases leave the engine at 125°C.