Question

$310$ g of a carbohydrate leaves a residue of $124$ g of carbon on heating in absence of air. If the empirical formula of the carbohydrate is $C_x{H}_y{O}_z$, then find the value of $x,y$ and $z$.

• A. $x=1,y=2,z=1$
• B. $x=2,y=4,z=2$
• C. $x=3,y=5,z=3$
• D. None of these

Answer 1

The correct option is A $x=1,y=2,z=1$

Given, a carbohydrate weighs $310$ g.
Carbon present = $124$ g
Water present $=310-124=186$ g.
Moles of Carbon $=\frac{124}{12}=10.03$
Moles of $H_{2}O=\frac{186}{18}=10.03$
$\therefore$ Ratio of $C:H_{2}O=1:1$
Hence, the empirical formula is $C{H}_{2}O$.