Wednesday

August 20, 2014

August 20, 2014

Posted by **sweety** on Friday, April 3, 2009 at 1:17am.

- physics -
**drwls**, Friday, April 3, 2009 at 1:47amUse the perfect gas law to get the number of moles, n. You can use initial condition values of p, V and T . The inital T is 296.5 K, V is 0.784 l and p = 1.017 atm. R = 0.08205 l-atm/mole

n = PV/RT = 0.0328 moles

The temperature after expansion depends upon the type of expansion. Usually an isentropic expansion is assumed, with the gas doing work while it pushes against an external boundary or gas. If it expands into a larger volume that had been previously empty, the gas temperature will not change.

For an isentropic expansion of a diatomic gas,

T^(5/2) * V = constant

The 5/2 exponent equals 1/[gamma - 1].

gamma = 1.4 for diatomics

(T'/296.5)^2.5 = 784/1170 = 0.670

T'/296.5 = 0.852

t' = 252.6 K = -20.6 C

- physics -
**sweety**, Friday, April 3, 2009 at 10:04amthank u so much for the help

- physics -
**drwls**, Friday, April 3, 2009 at 10:34amT' is supposed to be the final temperature

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