Dry air was drawn through bulbs containing a solution of 40 grams of urea in 300 gram of water, then through bulbs containing pure water at the same temperature and finally through a tube in which pumice moistened with strong.`H_(2)SO_(4)` was kept. The water bulbs lost 0.0870 grams and the sulphide acid tube gained 2.036 grams. Calculate the molecular weight of urea.

Answer

`M=53.8`

Explanation

Weight loss in first bulb `("w"_(1))prop"P"_("solution")`
weight loss in second bulb `("w"_(2))prop"P"^(0)-"P"_("solution")`
weight gain in tube `("w"_(1)+"w"_(2))prop"P"^(0)`
`("P"^(0)-"P"_("s"))/("P"_("s"))=("n"_("urea"))/("n"_("H"_(2)"O"))=("w"_(1))/("w"_(2))`
`"w"_(2)=0.0870`
`"w"_(1)=1.949`
`(40xx18)/("m"_("urea")xx300)=(0.0870)/(1.949)`
`"m"_("urea")=(40xx18xx1.949)/(300xx0.0870)=53.8"gm mol"^(-1)`