Question

Hydrogen gas is cooled from 300K to 150K. Its new pressure is 57.0 kPa. What answer is reasonable for the original pressure? Why?

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Answer 1

114kPa because p and T have a direct relationship

pV = nRT

p/T = nR/V

p/T = constant ---> direct proportionality (the ratio of the two is equal to a costant value)

So, if the pression increases the temperature increase of the same factor

T(strat) = 2 T(final) ---> p(start) = 2 p(final)

p(start) =2 x 57 kPa = 114 kPa