Calculate the total pressure in a 10 litre cylinder which contains `0.4g` of helium, `1.6g` of oxygen and `1.4g` of nitrogen at `27^(@)C`. Also calculate the partial pressure of helium gas in the cylinder. Assume ideal behaviour of gases. Given `R = 0.082` litre atm `K^(-1) mol^(-1)`.

Explanation

Give `V =10 litre, T =27 +273 =300K`
Mole of `He = (0.4)/(4) = 01, "Mole of" O_(2) =(1.6)/(32) = 0.5,`
Mole of `N_(2) = (1.4)/(28) = 0.05`
Total moles ` =0.1 xx 0.05 + 0.05 =0.20`
`P_(M) = (nRT)/(V) = (0.2 xx 0.082 xx 300) /(100) = 0.492 atm`
`:. P'_(He) = P_(M) xx` Mole fration of `He = 0.492 xx (0.1)/(0.2)`
` =0.246 atm`
`P'_(O_(2)) =P_(M) xx` Mole fration of `O_(2) =0.492 xx (0.05)/(0.2)`
` = 0.123 atm`
`P'_(N_(2)) = P_(M) xx` Mole fraction of `N_(2) = 0.492 xx (0.05)/(0.2)`
` =0.123` atm .