Aclosed tank having a volume of 2 ft3 is filled with 0.30 lb of a gas. a pressure gage attached to the tank reads 12 psi when the gas temperature is 80 f. there is some question as to whether the gas in the tank is oxygen or helium. which do you think it is? explain how you arrived at your answer.

Solution:

p = PRT; P = P/RT

p = 12 psi + 14.7 psi = 26.7 psiT = 80 degrees Fahrenheit = 540 degrees R--
The density of the tank’s gas= 0.30 lb / 32.2 ft/s^2 divided by 2ft^3= 4.66 x 10^-3 

= If the gas was oxygen:P = 26.7 (184) (lb/ft) divided by 1.554 x 10^3 [ft lb/swg degrees r] 54- degrees RPoxgen = 4.59 x 10^-3

If the gas was helium:Phelium = 7.17 divided by 1.242 x 10^3 = 5.73 x 10^-4

Therefore, the gas must be oxygen.

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