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A 100cm^3 box (1X10^-4 m^3) contains helium at a pressure of 2.0 atm and at a temperature of 100C (373K) It is placed in thermal contact with a 200cm^3 (2x10^-4 m^3) box containing argon at a pressure of 4.0atm and a temp. of 400C (673K)
a) What is the initial thermal energy of each gas?
b) final thermal energy?
c)How much heat is transferred?
d)Final Temp?
e)Final pressure of each?
OK, I got part a).
First I used [tex] PV = nRT [/tex] to solve for the mols of each gas. Then I used
[tex] E_{th} = 3/2nRT[/tex]
to find the thermal energy of each gas.
Helium- .007mol, 30.4 J
Argon- .0145 mol, 121.6J
These answers for the initial thermal energy are right. My problem starts in part B.
To find the thermal energy of gas A you'd use the formula:
[tex] E_A = \frac{n_A}{n_A+n_B}E_{total} [/tex]
When I use this formula to find the final thermal energy of Helium I get:
[tex] E_{He} = \frac{n_{He}}{n_{He}+n_{Ar}}E_{total} [/tex]
[tex] \frac{.007}{.0215}(152J) = 49.5 J [/tex]
That would also give me 102.5 J for Argon. Both of these final thermal energies are wrong according to the book but I can't see my mistake. Because of this I get part c, d, and e wrong also. Can someone help me out here? Thanks.
a) What is the initial thermal energy of each gas?
b) final thermal energy?
c)How much heat is transferred?
d)Final Temp?
e)Final pressure of each?
OK, I got part a).
First I used [tex] PV = nRT [/tex] to solve for the mols of each gas. Then I used
[tex] E_{th} = 3/2nRT[/tex]
to find the thermal energy of each gas.
Helium- .007mol, 30.4 J
Argon- .0145 mol, 121.6J
These answers for the initial thermal energy are right. My problem starts in part B.
To find the thermal energy of gas A you'd use the formula:
[tex] E_A = \frac{n_A}{n_A+n_B}E_{total} [/tex]
When I use this formula to find the final thermal energy of Helium I get:
[tex] E_{He} = \frac{n_{He}}{n_{He}+n_{Ar}}E_{total} [/tex]
[tex] \frac{.007}{.0215}(152J) = 49.5 J [/tex]
That would also give me 102.5 J for Argon. Both of these final thermal energies are wrong according to the book but I can't see my mistake. Because of this I get part c, d, and e wrong also. Can someone help me out here? Thanks.