Question

If a sample of helium gas at 870 torr and 22 degrees C is allowed to expand from 23 L to 55 L without changing the temperature, what pressure will the helium gas exert?

Answer 1

Well, for a start...the measurement of pressure is illegitimate...

Explanation:

We know that one atmosphere will support a column of mercury that is `760*mm` high. A mercury column is thus a good measure for pressures at `1*atm` or much LOWER than `1*atm`..

And so here `P=(870*mm*Hg)/(760*mm*Hg*atm^-1)=1.15*atm`.

And so `P_1V_1=P_2V_2`...and `P_2=(P_1V_1)/V_2`

`=(1.15*atmxx23*L)/(55*L)=0.479*atm-=363.8*mm*Hg`