Question

A cylinder if fitted with a floating piston oriented horizontally (the air is the system and by having a floating piston it maintains constant pressure). It contains 24.5 L of air at 25.0C and 1 bar pressure. The system is then heated to 250.0C. Air can be considered a diatomic gas and therefore would have a Cv = 5R/2, where R is the ideal gas constant. Also for gases Cp = Cv +R. How much work was done (in J) and how much heat was transferred?

Answer #1

if constant pressure, then

P1 = P2

1 bar = P2

At constant P

Q = dH is true

dH = n*Cp*dT

get n

n = PV/(RT) = 1*24.5/(0.08314*295) = 0.99892 mol

Cp = Cv + R = 5/2*R + R = 7/2R = 7/2*8.314 = 29.099 J/molK

Q = dH = n*Cp*(/Tf-Ti) = (0.99892)(29.099)(250-25)

**Q = 6540.203 J**

b)

if =P constant

W = -P*(Vf-Vi)

Vi = 24.5 L

Vf = from

V1/T1 = V2/T2

Vf = (250+273)/(25+273) * 24.5 = 42.998 = 43 L

P = 1 bar = 10^5 Pa 1 m3 = 10^3 L

W = -(1*10^5)(43-24.5)*10^-3

W = -1850 J = -1.85 kJ

**W = - 1850 J = -1.85 kJ**

One gram-mole of ideal gas is contained in a piston-cylinder
assembly. Cp=(7/2)R, Cv=(5/2)R. The gas expands from 3 to 1 atm.
Heat of 1000J is transferred to the gas during the process.
External pressure maintains at 1 atm throughout. Initial
temperature of the gas is 300K. Find work and internal energy
change.

A cylinder is fitted with a piston, beneath which is a spring,
as in the drawing. The cylinder is open to the air at the top.
Friction is absent. The spring constant of the spring is 3700 N/m.
The piston has a negligible mass and a radius of 0.032 m. (a) When
the air beneath the piston is completely pumped out, how much does
the atmospheric pressure cause the spring to compress? (b) How much
work does the atmospheric pressure...

A 6.0-cm-diameter cylinder of nitrogen gas has a 4.0-cm-thick
movable copper piston. The cylinder is oriented vertically, as
shown in the figure, and the air above the piston is evacuated.
When the gas temperature is 15 ∘C , the piston floats 20cm above
the bottom of the cylinder.
A. What is the gas pressure?
B. How many gas molecules are in the cylinder?
C. Then 1.5 JJ of heat energy are transferred to the
gas. What is the new equilibrium temperature...

In a cylinder/piston arrangement, air is compressed in a
reversible polytropic process to a final state of 800 kPa, 500 K.
Initially air is at 110 kPa and 25oC. During the
compression process heat transfer takes place with the ambient
maintained at 25oC. Assume air as an ideal gas (R =0.287
kJ/kg) and has constant specific heats of Cp = 1.004
kJ/kgK and Cv = 0.717 kJ/kgK. If the mass of air in the
cylinder is 0.1286 kg, determine
a)...

A 0.2 m3 piston-cylinder initially contains 400 K air. A heavy
frictionless piston maintains a pressure of 500 kPa abs. Then, a
weakness in the cylinder wall blows out and creates a hole. Air
escapes through the hole until the piston drops far enough to cover
the hole. At that point, the volume is half the initial volume.
During this process, 75 kJ of heat is transferred to the 100 kPa,
300 K surroundings. Using Cp = 1.005 kJ/kg-K and...

An insulated cylinder is fitted with an airtight piston that is
free to slide up and down and is connected to a rod, as shown in
the figure. Contained within the cylinder is an ideal gas initially
at a pressure of 120 kPa and temperature of 293 K. Suddenly the
piston is forced downward creating an additional 200 kPa of
pressure on the gas and as a result the cylinder volume decreases
to one-half of its original volume. (a) What...

A cylinder contains 1.5 moles of ideal gas, initially at a
temperature of 113 ∘C. The cylinder is provided with a frictionless
piston, which maintains a constant pressure of 6.4×105Pa on the
gas. The gas is cooled until its temperature has decreased to 27∘C.
For the gas CV = 11.65 J/mol⋅K, and the ideal gas
constant R = 8.314 J/mol⋅K.
1.Find the work done by the gas during this process.
2.What is the change in the internal (thermal) energy of...

An insulated cylinder is fitted with an airtight piston that is
free to slide up and down and is connected to a rod. Contained
within the cylinder is an ideal gas initially at a pressure of 120
kPa and temperature of 293 K. Suddenly the piston is forced
downward creating an additional 200 kPa
of pressure on the gas and as a result the cylinder volume
decreases to one-half of its original volume.
(a) What is the final temperature of...

Your new engine design consists of a piston cylinder
arrangement. The engine operates with mostly air and a small amount
of fuel. The system undergoes a cycle. The initial Pressure and
temperature are p1= 1bar and T1= 27°C. The system undergoes a power
cycle consisting of the following process:
Process
1-2
constant volume to a pressure, P2 of 4 bars
Process
2-3
expansion of pv=constant
Process 3-1
constant-pressure compression
Draw the system and pv diagrams
If P2 is 4...

A cylinder of monatomic ideal gas is sealed in a cylinder by a
piston. Initially, the gas occupies a volume of 3.00 L and the
pressure is initially 105 kPa. The cylinder is placed in an oven
that maintains the temperature at a constant value. 65.0 J of work
is then done on the piston, compressing the gas (in other words,
the gas does −65.0 J of work). The work is done very slowly so that
the gas maintains a...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 2 minutes ago

asked 3 minutes ago

asked 3 minutes ago

asked 11 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 16 minutes ago

asked 17 minutes ago