Two moles of a monoatomic perfect gas initially 4.0 bars and 470C unde...
Given:
- Two moles of a monoatomic perfect gas
- Initial pressure (P1) = 4.0 bar
- Initial temperature (T1) = 470C
- Final pressure (P2) = 3.0 bar
- Process is reversible and adiabatic (insulated container)
To find: Final temperature (T2)
Formula used:
- For reversible adiabatic process, PV^γ = constant, where γ = Cp/Cv for a monoatomic gas is 5/3
- Also, PV = nRT (Ideal gas equation)
Solution:
1. Using the ideal gas equation, we can find the initial volume (V1) of the gas:
PV = nRT
V1 = nRT1/P1 = 2 x 8.314 x (470+273)/4.0 = 0.078 m3
2. Using the initial pressure and volume, we can find the initial value of PV^γ:
PV^γ = (4.0 bar x 0.078 m3)^5/3 = 1.10 x 10^6 bar3/K5/3
3. Since the process is reversible adiabatic, PV^γ remains constant:
P1V1^γ = P2V2^γ
4. Using the final pressure (P2) and the constant value of PV^γ, we can find the final volume (V2):
V2 = (P1V1^γ/P2)^(1/γ) = (1.10 x 10^6 bar3/K5/3 / 3.0 bar)^(1/5/3) = 0.105 m3
5. Using the final volume and the ideal gas equation, we can find the final temperature (T2):
PV = nRT
T2 = P2V2/nR = 3.0 bar x 0.105 m3 / 2 x 8.314 = 285 K
Therefore, the final temperature at which the pressure reduces to 3.0 bar is 285 K, which is option B.
Two moles of a monoatomic perfect gas initially 4.0 bars and 470C unde...
Given information:
- Two moles of a monoatomic perfect gas
- Initial pressure (P1) = 4.0 bar
- Initial temperature (T1) = 470°C
- Final pressure (P2) = 3.0 bar
- The process is reversible and adiabatic
To find: The final temperature (T2) at which the pressure reduces to 3.0 bar.
Formula used:
For an adiabatic process, PVγ is constant, where P is the pressure, V is the volume, and γ is the ratio of specific heats (Cp/Cv) for the gas. For a monoatomic perfect gas, γ = 5/3.
Calculation:
Using the formula PVγ = constant, we can write:
P1V1γ = P2V2γ
Since the gas is monoatomic, we can use the ideal gas law to relate the pressure, volume, and temperature:
PV = nRT
where n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.
Substituting this expression for V in the first equation and simplifying, we get:
(P1/P2) = (T2/T1)^(γ-1)
(4.0/3.0) = (T2/743)^(2/3)
(T2/743) = (3/4)^(3/2)
T2 = 285 K
Therefore, the final temperature at which the pressure reduces to 3.0 bar is 285 K.
Answer: b) 285 K