Question

0.07g of anhydride of carbon occupies 56dm³ at stp when vaporized.and contains 14.29% by mass hydrogen.what is the mass of the hydrocarbon.

Answer 1

Since the sample is a hydrocarbon, it contains Carbon and hydrogen in a specific ratio.

$1GMW=22.4dm^3$

Molar mass of Hydrocarbon $=56dm^3$

$1GMW$ of $CO_2=12+2\times24=44gm=12gm Carbon$

$=$ $12\over44$ $\times 0.07=0.0191$

$\%$ Carbon in the sample$=85.71\%$

$\%$ Hydrogen in the sample $=14.29\%$

Empirical formualr$=$ $85.71\over 12.01$ $=7.14$

.$14.29\over 1.0079$ $=14.29$

$=1:2$

Formulae of Hydrocarbon$=(CH_2)_n$

$=(12.011+2\times 1.0079)\times n=56$

$=14.0268n=56$

$n=3.99=4$

$C_4H_8$

Mass of Hydrocarbon $=(12.011\times 4)+(1.0079\times 8)$

$=56.1072g$