One litre flask containing vapour of methyl alcohol (Mol mass 32) at a pressure of 1 atm. And 25^(@)Cwas evacuated till the final pressure was 10^(-3)mm. How many molecules of methyl alcohol were left in the flask ?

One litre flask containing vapour of methyl alcohol (Mol mass 32) at a

1.	One litre flask containing vapour of methyl alcohol (Mol mass 32) at a pressure of 1 atm. And 25^(@)Cwas evacuated till the final pressure was 10^(-3)mm. How many molecules of methyl alcohol were left in the flask ?
Answer» Solution :`P_(1)=10^(-3)MM, V_(1)=1000 cm^(3), T_(1)=298 K` For converting this volume to volume at S.T.P. , apply `(P_(1)V_(1))/(T_(1))=(P_(2)V_(2))/(T_(2)), i.e., (10^(-3)xx1000)/(298)=(760xxV_(2))/(273)"or" V_(2)=1.205xx10^(-3)cm^(3)` `22400 cm^(3)` at S.T.P.`-=6.02xx10^(23)` molecules `:. 1.205xx10^(-3)cm^(3)` at S.T.P. `-=(6.02xx10^(23))/(22400)xx1.025xx10^(-3)` molecules `=3.24xx10^(16)` molecules