- #1
Spectre5
- 182
- 0
I have this problem and I do not have the answer, but I get an answer that I feel is probably wrong, so can someone please check my work and point out where I went wrong??
Here is the problem:
moles = 0.10 of O_2
T(initial) = 150 C = 423 K
P(initial) = 3.0 atm = 303.9 KPa
The gas expands adiabatically until the pressure is halved, find the final volume and final pressure
Since the pressure is halved, we know that
P(final) = 1.5 atm = 151.95 KPa
I need the initial volume, so I used the ideal gas equation, PV = nRT
using the initial conditions with P in pascals, n in mols, T in kelvin, and R as 8.31 J/mol*K
So I get a V(initial) = 1.156 x 10^(-3) m^3
Then I need the final volume, and since this is adiabatic,
Pi(Vi)^(gamma)=Pf(Vf)^(gamma)
Since O_2 is diatomic and we assume ideal conditions, gamma = 1.4
So using the above equation, I find
V(final) = 1.37 x 10^(-5) m^3 = answer to part a
I don't know if this is right or wrong
Then for part b, I used the idea gas equaion again, PV=nRT
Using the final volume, final pressure, same n and same R, I get
T = 2.50 K
Obviously this is extremely COLD! I don't think it makes sense that the temperature would drop from 423 K to 2.5 K...where did I go wrong?
Here is the problem:
moles = 0.10 of O_2
T(initial) = 150 C = 423 K
P(initial) = 3.0 atm = 303.9 KPa
The gas expands adiabatically until the pressure is halved, find the final volume and final pressure
Since the pressure is halved, we know that
P(final) = 1.5 atm = 151.95 KPa
I need the initial volume, so I used the ideal gas equation, PV = nRT
using the initial conditions with P in pascals, n in mols, T in kelvin, and R as 8.31 J/mol*K
So I get a V(initial) = 1.156 x 10^(-3) m^3
Then I need the final volume, and since this is adiabatic,
Pi(Vi)^(gamma)=Pf(Vf)^(gamma)
Since O_2 is diatomic and we assume ideal conditions, gamma = 1.4
So using the above equation, I find
V(final) = 1.37 x 10^(-5) m^3 = answer to part a
I don't know if this is right or wrong
Then for part b, I used the idea gas equaion again, PV=nRT
Using the final volume, final pressure, same n and same R, I get
T = 2.50 K
Obviously this is extremely COLD! I don't think it makes sense that the temperature would drop from 423 K to 2.5 K...where did I go wrong?