**how it arrive to this answer?**

**please show a solution**

**Answer : 15.43 lb; 10 ft^3; 308.5 psia**

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3. A 10 ft^3 tank contains gas at a pressure of 500 psia, temperature of 85 Fahrenheit and a weight of 25 lbs. A part of the gas was discharged and the temperature and pressure changed to 70 fahrenheit and 300 psia, respectively. Heat was applied and the temperature was back to 85 fahrenheit. Find the final weight, volume, and pressure of the gas.

**how it arrive to this answer?** **please show a solution**

**Answer : 15.43 lb; 10 ft^3; 308.5 psia**

Why should we if you don't show us how you try first?

Hi Justine,

Convert your Fahrenheit temperatures into degrees Kelvin [Moderator: Somewhat easier, and just as effective, if more obscure, degrees Rankine -- see the earlier post. http://www.physforum.com/index.php?showtopic=26658 ].. if you can do that then anyone (even me, probably even you) can answer the question.

-C2.

Convert your Fahrenheit temperatures into degrees Kelvin [Moderator: Somewhat easier, and just as effective, if more obscure, degrees Rankine -- see the earlier post. http://www.physforum.com/index.php?showtopic=26658 ].. if you can do that then anyone (even me, probably even you) can answer the question.

-C2.

So this setup is the same as before:

P₁V₁/N₁T₁ = P₂V₁/N₂T₂ = P₃V₁/N₂T₃

So N₂ = (T₁/T₂)(P₂/P₁)N₁

And P₃ = (N₂/N₁)(T₃/T₁)P₁ = (T₃/T₂)P₂

Oh, and the weight of the gas is proportional to N.

Oh, and for this problem, T₃ =T₁.

Finally, your book has some odd convention with respect to rounding.

P₁V₁/N₁T₁ = P₂V₁/N₂T₂ = P₃V₁/N₂T₃

So N₂ = (T₁/T₂)(P₂/P₁)N₁

And P₃ = (N₂/N₁)(T₃/T₁)P₁ = (T₃/T₂)P₂

Oh, and the weight of the gas is proportional to N.

Oh, and for this problem, T₃ =T₁.

Finally, your book has some odd convention with respect to rounding.

Hi Sir,

Thanks for giving me some insight about this, sorry because i am trying but I can't get the correct answer. The book has answer but no slution thats why I included the answer...Thanks again and more power...

Thanks for giving me some insight about this, sorry because i am trying but I can't get the correct answer. The book has answer but no slution thats why I included the answer...Thanks again and more power...

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