Question

A compound has $50$% carbon, $50$% oxygen and approximate molecular weight is $290.$ Its molecular formula is

• A. $CO$
• B. $C_4{O}_3$
• C. $C_{12}{O}_9$
• D. $C_3{O}_3$

Answer 1

Answer: (C)

$C_{12}{O}_9$

Element mass %	No. of moles	Simple ratio
$C=50\%$	$\frac{50}{12}$	$4$
$O=50\%$	$\frac{50}{16}$	$3$

Empirical formula $=C_4{O}_3$

Empirical formula mass $=96$

$n=\frac{290}{96}=3$

Molecular formula $=(C_4{O}_3{)}_3=C_{12}{O}_9$.