Question

An organic compound contains 88.89% carbon and 11.11% hydrogen by mass. The molecular mass of the organic compounds is 54g:mol. Find the molecular formula of the compound.

Answer 1

Solution.

$w(C)=88.89\%;$

$w(H)=11.11\%;$

$M(C_xH_y)=54g/mol;$

$x:y=\dfrac{w(C)}{Ar(C)}:\dfrac{w(H)}{Ar(H)}=\dfrac{88.89}{12}:\dfrac{11.11}{1}=7.4075:11.11=1:1.5=10:15=2:3;$

$C_2H_3;$

$M(C_2H_3)=2\sdot12+3=27g/mol;$

Since $M(C_2H_3)=27g/mol$ , and in the condition 54g / mol, so the indices need to be doubled.

$C_4H_6;$

$M(C_4H_6)=12\sdot4+6=54g/mol;$

Answer: $C_4H_6.$