$7-1.$ Use a vacuum inerting procedure with nitrogen to reduce the oxygen concentration to $1$ ppm$.$

The vessel has a volume of $3\mathrm{.}78$ m$3$

and initially contains air, the vacuum system can deliver $20$ mm

Hg absolute$,$ the temperature is $24\backslash$deg C$,$ and the highest pressure is $1$ atm. Determine the number of

purges and the total amount of nitrogen used $($in kg$).$ Repeat for a vessel with a volume of $37$ m$3$

and a vacuum of $30$ mm Hg$.$