Question

A colorless liquid used in rocket engines, whose empirical formula is $NO_{2}$, has a molar mass of 92. What is its molecular formula?

Answer 1

From the given,

A colorless liquid is used as rocket fuel.

The empirical formula of colorless liquid: $N{ O }_{ 2 }$

The molar mass of $N{ O }_{ 2 }$ is 92 g/mol.

Let's find the molecular formula of the $N{ O }_{ 2 }$

$Molecular\quad formula\quad =\quad empirical\quad formula\quad \times \quad n\quad factor$

$n\quad factor\quad =\quad \frac { Formula\quad mass }{ Molar\quad mass }$

$Formula\quad mass\quad =\quad N{ O }_{ 2 }\quad =\quad 14\quad +\quad 2(16)\quad =\quad 46$

$n\quad =\quad \frac { 46 }{ 98 } \quad =\quad 2$

$molecular\quad formula\quad =\quad 2\quad \times \quad N{ O }_{ 2 }\quad =\quad { N }_{ 2 }{ O }_{ 4 }$

Therefore, molecular formula of colourless liquid which is used in rocket fuel is ${ N }_{ 2 }{ O }_{ 4 }$