Question

1. A dry air mass ascends in the atmosphere from the 100 kPa level to the 50 kPa level. Assuming that it does not mix or exchange heat with its surroundings, and that the initial temperature is 283 K, calculate: a) the initial specific volume at 100 kPa b) the final temperature at 50 kPa c) the final specific volume at 50 kPa d) the change in specific enthalpy (dh) and specific internal energy (du) during the ascent from 100 to 50 kPa e) the work of expansion done by 1 m³ of air as it rises from 100 to 50 kPa (note that this is not 'dw', rather it is 'w'). f) what would the specific enthalpy change have been for an isobaric cooling to the same final temperature? g) what would the specific enthalpy change have been for an isothermal expansion to the same final pressure? 2. Using the assumption that argon is a monoatomic gas and has an atomic weight of 39.95 g mole?¹, recompute Problem 1 for an atmosphere of pure argon. 3. An insulated box contains two sections A and B. Each section contains a diatomic ideal gas. The sections are separated by an insulating perfectly flexible wall. Initially the pressure is the same on both sides (1.01325 x 10? Pa) and the volumes are the same (10?³ m³). (HINT: Sketching the problem will help!!!) Heat is supplied to gas A by means of an electrical resistance (a hot wire) until the pressure rises to 1.01326 x 10? Pa. If the perfectly flexible wall allows both gases to maintain equal pressures and the initial temperature of both gases is 273 K, compute: a) the final temperature of side B b) the work performed on gas B c) the final temperature of side A d) the heat absorbed by gas B (Hint: there are a number of things you have to find before you can answer those questions... a sketch of the problem is an excellent beginning. Another hint: think about "adiabatic" and to what gases can it be applied.) 4. Compute problem 3d if the gases were monatomic ideal gases. 5. Consider one mole of air initially at 273 K and 10? Pa. Through a process in which pV? = constant (Note n ? ?), the volume of air triples by the time it reaches a pressure of 2.5 x 10? Pa. Calculate: a) the value of n b) the final temperature at 2.5 x 10? Pa (Hint use form of equation of state: pV = N R* T where N is the number of moles) c) the change in internal energy d) the work done by the gas e) the heat absorbed by the gas

          1. A dry air mass ascends in the atmosphere from the 100 kPa level to the 50 kPa level. Assuming that it does not mix or exchange heat with its surroundings, and that the initial temperature is 283 K, calculate:
a) the initial specific volume at 100 kPa
b) the final temperature at 50 kPa
c) the final specific volume at 50 kPa
d) the change in specific enthalpy (dh) and specific internal energy (du) during the ascent from 100 to 50 kPa
e) the work of expansion done by 1 m³ of air as it rises from 100 to 50 kPa (note that this is not 'dw', rather it is 'w').
f) what would the specific enthalpy change have been for an isobaric cooling to the same final temperature?
g) what would the specific enthalpy change have been for an isothermal expansion to the same final pressure?

2. Using the assumption that argon is a monoatomic gas and has an atomic weight of 39.95 g mole?¹, recompute Problem 1 for an atmosphere of pure argon.

3. An insulated box contains two sections A and B. Each section contains a diatomic ideal gas. The sections are separated by an insulating perfectly flexible wall. Initially the pressure is the same on both sides (1.01325 x 10? Pa) and the volumes are the same (10?³ m³). (HINT: Sketching the problem will help!!!)
Heat is supplied to gas A by means of an electrical resistance (a hot wire) until the pressure rises to 1.01326 x 10? Pa. If the perfectly flexible wall allows both gases to maintain equal pressures and the initial temperature of both gases is 273 K, compute:
a) the final temperature of side B
b) the work performed on gas B
c) the final temperature of side A
d) the heat absorbed by gas B
(Hint: there are a number of things you have to find before you can answer those questions... a sketch of the problem is an excellent beginning. Another hint: think about "adiabatic" and to what gases can it be applied.)

4. Compute problem 3d if the gases were monatomic ideal gases.

5. Consider one mole of air initially at 273 K and 10? Pa. Through a process in which pV? = constant (Note n ? ?), the volume of air triples by the time it reaches a pressure of 2.5 x 10? Pa. Calculate:
a) the value of n
b) the final temperature at 2.5 x 10? Pa (Hint use form of equation of state: pV = N R* T where N is the number of moles)
c) the change in internal energy
d) the work done by the gas
e) the heat absorbed by the gas

1. A dry air mass ascends in the atmosphere from the 100 kPa level to the 50 kPa level. Assuming that it does not mix or exchange heat with its surroundings, and that the initial temperature is 283 K, calculate:
a) the initial specific volume at 100 kPa
b) the final temperature at 50 kPa
c) the final specific volume at 50 kPa
d) the change in specific enthalpy (dh) and specific internal energy (du) during the ascent from 100 to 50 kPa
e) the work of expansion done by 1 m³ of air as it rises from 100 to 50 kPa (note that this is not 'dw', rather it is 'w').
f) what would the specific enthalpy change have been for an isobaric cooling to the same final temperature?
g) what would the specific enthalpy change have been for an isothermal expansion to the same final pressure?

2. Using the assumption that argon is a monoatomic gas and has an atomic weight of 39.95 g mole?¹, recompute Problem 1 for an atmosphere of pure argon.

3. An insulated box contains two sections A and B. Each section contains a diatomic ideal gas. The sections are separated by an insulating perfectly flexible wall. Initially the pressure is the same on both sides (1.01325 x 10? Pa) and the volumes are the same (10?³ m³). (HINT: Sketching the problem will help!!!)
Heat is supplied to gas A by means of an electrical resistance (a hot wire) until the pressure rises to 1.01326 x 10? Pa. If the perfectly flexible wall allows both gases to maintain equal pressures and the initial temperature of both gases is 273 K, compute:
a) the final temperature of side B
b) the work performed on gas B
c) the final temperature of side A
d) the heat absorbed by gas B
(Hint: there are a number of things you have to find before you can answer those questions... a sketch of the problem is an excellent beginning. Another hint: think about "adiabatic" and to what gases can it be applied.)

4. Compute problem 3d if the gases were monatomic ideal gases.

5. Consider one mole of air initially at 273 K and 10? Pa. Through a process in which pV? = constant (Note n ? ?), the volume of air triples by the time it reaches a pressure of 2.5 x 10? Pa. Calculate:
a) the value of n
b) the final temperature at 2.5 x 10? Pa (Hint use form of equation of state: pV = N R* T where N is the number of moles)
c) the change in internal energy
d) the work done by the gas
e) the heat absorbed by the gas

Added by Julia G.

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