Question

Air with a mass of 2 kg is heated at a constant pressure of
200 kPa to a temperature

of 500°C. Calculate the entropy change if the initial volume
is 0.8 m3. Take ???? =

1.00 kJ/kg ? K and model air as an ideal gas. (Hint: Use the
appropriate TdS [Gibbs] relation to calculate entropy
change.)

Answer #1

Air is contained in a rigid, well-insulated container
of volume 3 m3. The air undergoes a process from
an initial state with a pressure of 200 kPa and temperature of 300
K. During the process, the air
receives 720 kJ of work from a paddle wheel. Model the air as an
ideal gas with constant specific
heats. Evaluate the specific heats at 300 K. Neglect changes in
kinetic energy and potential energy.
Determine the mass of the air in kg,...

500 kg of saturated liquid at 11 MPA is heated at constant
pressure until it reaches a temperature of 450 C find the
following: a. enthalpy entropy and specific volume at the end of
the process b. change in entropy in kj/kg k of the process c.
amount of heat needed for the process

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...

2-Assuming ideal gas and constant Cp, calculate [capital delta S
with hat on top] (in kJ/(kg?K)) for a process where nitrogen is
heated from 200 K to 800 K while changing the pressure from 2000
kPa to 1000 kPa.
1-Using the thermodynamic tables, calculate [capital delta S with
hat on top] (in kJ/(kg?K)) for a process where nitrogen is heated
from 200 K to 800 K while changing the pressure from 2000 kPa to
1000 kPa.

Steam is heated from 10 kPa and 50°C to 550 kPa and 500°C.
Calculate the change in entropy:
a) If the steam is considered an ideal gas.
b) If the steam is not considered an ideal gas.
c) Discuss if it is appropriate to consider steam an ideal gas for
this process.

Oxygen gas is contained in a piston cylinder assembly at an
initial pressure of 1000 kPa and expands from 0.2 m3 to 1.0 m3 by a
process where PV = constant. The gas has an internal energy change
of -200 kJ. Calculate the work (kJ) and the heat transfer (kJ) done
during the process.

Use cold-air-standard analysis with the fluid modeled as an
ideal gas with R=0.287 kJ/kg-K and constant k=1.4. Neglect changes
in kinetic and potential energy. Consider a SSSF of air at 300 K
and 100 kPa entering the compressor of a Simple Brayton Cycle Gas
Turbine powerplant. The cycle pressure ratio is 40 and maximum
cycle temperature is 1800 K. For compressor isentropic efficiency
of 82% the compressor work input per unit mass = __ kJ/kg (enter
the nearest positive integer...

Atmospheric pressure is 100 kPa in a system of cylinders and pistons.The mass of the piston is 4 kg and the area of the piston is 4.0 cm2. The following process takes place by external heat transfer. (Gravity acceleration is 10 m / s2).
1. Calculate the pressure inside the cylinder in kPa.
2. The cylinder contains 0.1 kg of water vapor, and the
temperature of the water vapor is 150oC. Find the volume and
internal energy of water vapor...

An ideal monatomic gas is contained in a vessel of constant
volume 0.330 m3. The initial temperature and pressure of the gas
are 300 K and 5.00 atm, respectively. The goal of this problem is
to find the temperature and pressure of the gas after 24.0 kJ of
thermal energy is supplied to the gas.
(a) Use the ideal gas law and initial conditions to calculate
the number of moles of gas in the vessel. Your response differs
from the...

An ideal gas is heated under constant pressure (Pext
= 2 bar) from an initial volume of 1 liter and temperature
250C to a final temperature of 370C. what is
the final volume of the gas? how many moles of gas are
involved?

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