CONSTANTS: 1 cal = 4.186
J
1 atm = 1.01 x 10^{5} N/m^{2}

1] An ideal gas has a volume of 22.4 x 10^{-3} m^{3}
at zero degrees Celsius and one atmosphere

pressure. The gas absorbs 315 cal of heat from the surroundings
and expands isobarically to

32.4 x 10^{-3} m^{3} . What is the change in
the internal energy of the gas?

Answer: DU = 310 J

2] A heat engine absorbs 1500 J of energy each cycle and
exhausts
1000 J of energy each cycle.

Determine the maximum efficiency and work output per cycle of the
engine.

Answer: 33% , 500 J

3] An ideal heat engine is designed to produce 5000 J of work when
it
uses a hot reservoir

providing 12,500 J of heat energy. If the engine will typically have
an exhaust temperature of

25 ^{o}C, what must the temperature of the hot reservoir be
in degrees Celsius?

Answer: 224 degrees Celsius

4] A cylinder with a movable piston contains 9.0 grams of steam with
the following properties:

pressure is 5.5 atmospheres, volume is 3.0 liters, temperature is 130
^{o}C
. Under__ constant__

__pressure__, heat is added to the steam such that the piston moves
up (volume increases) until the

steam temperature is 250 ^{o}C . What is the change in the
internal energy of the steam for this

process?

Answer: +1700 J

5] A heat engine is designed to produce 3000 J of work when it uses
a hot reservoir of

temperature 200 ^{o}C and has an exhaust temperature of 25
^{o}C.
Determine the maximum

efficiency of the engine and the heat lost to the surroundings each
cycle.

Answer: e = 37% , Q = 5100 J

6] 100 grams of water is in a closed container of volume 500 cm^{3}
. At a constant pressure of

2.50 atmospheres and a constant temperature of 100 ^{o}C, the
water is turned into steam that

fills the container. What is the change in the internal energy of the
water molecules for this

process?

Answer: 2.26 x 10(5) Joules

M
ULTIPLE CHOICE

1) An ideal gas is quickly compressed in an insulated
environment. During this process, the gas exchanges no energy

(or heat) with its
surroundings. The process is thus an ___________
process.

a. isothermal

b. isometric

c. isobaric

d. adiabatic

2) An ideal gas is compressed to one-half its original volume
during an isothermal process. The final pressure of the gas

a. increases to twice its original
value

b. increases to less than twice its
original value

c. increases to more than twice its
original value

d. does not change

e. decreases to one-half its
original value

3) When water freezes, the entropy of the water

a. increases

b. decreases

c. does not change

d. could either increase or
decrease depending on the pressure

4) The 2nd law of thermodynamics leads us to conclude that

a. the total energy of the
universe is constant

b. disorder in the universe is
increasing with the passage of time

c. it is theoretically possible
to convert energy into work with 100% efficiency

d. the average temperature of the
universe is increasing with the passage of time

5) The Carnot cycle is the most efficient heat engine
cycle. If the efficiency of a Carnot engine were to be

%100, the exhaust reservoir would have
to be

a. infinitely hot

b. at a temperature of 0 degrees
Celsius

c. at a temperature of 100
degrees Celsius

d. at absolute zero

e. at any tempertures since a
Carnot engine always has 100% efficiency

Answers

1. d

2. a

3. b

4. b

5. d