Hydrogen gas in 500cm^3 container at a pressure of 700 torr is transferred to a container of volume 700 cm^3. What will the new pressure be? a) if no temperature change occurs. b) if it's temperature changes from 25C to 35C?

1 Answer
anor277
Apr 23, 2017

Well, the combined gas law holds that #(P_1V_1)/T_1=(P_2V_2)/T_2#, so..................

Explanation:

So we solve for #P_2#, and thus #P_2=(P_1V_1)/T_1xxT_2/V_2#, which clearly has the required units of pressure; why?

#P_2=(500*cancel(cm^3)xx700*"Torr")/(700*cancel(cm^3))=500*"Torr"#

The beauty of using these gas laws, is that (excluding temperature) given the proportionality, we can use whatever outlandish units we want, i.e. #"pounds per square inch, pints, furlongs"^3#.

And for part (b), we must use units of #"absolute temperature"#, #T_1=298*K; T_2=308*K#:

#P_2=(700*"Torr"*500*cm^3)/(298*K)xx(308*K)/(700*cm^3)#,

#=517*"mm Hg"#

What are these pressure in #"atmospheres"#?

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