In a Victor Meyer's determination, 0.23 g of a volatile substance displaced air which measured 112 mL at S.T.P. Calculate the vapour density and molecular weight of the substance (1 litre of H_2 at S.T.P. weighs 0.09 g).

In a Victor Meyer's determination, 0.23 g of a volatile substance disp

1.	In a Victor Meyer's determination, 0.23 g of a volatile substance displaced air which measured 112 mL at S.T.P. Calculate the vapour density and molecular weight of the substance (1 litre of H_2 at S.T.P. weighs 0.09 g).
Answer» SOLUTION :Vapour density of a GAS is GIVEN by `V.D. =(" WEIGHT of a definite volume of gas at S.T.P.")/("Weight of the same volume of" H_2 "at S.T.P.")` In the present case, 112 mL of the vapour of the given substance weighs 0.23 g. The weight of similar volume (112 mL) of H2 at S.T.P. will be `=(0.09)/1000 xx 112 = 0.01008 g` `:." The V.D. of the given substance " (0.23)/(0.01008)= 22.82` The molecular weight is related to V.D. as Molecular weight `= 2 xx V.D`. Hence, the molecular weight of the given substance `= 2 xx 22.82 = 45.64`