Question

An oxide of Nitrogen contains 63.1% Oxygen and has a molar mass of 76.0 g/mol

Answer 1

An oxide of nitrogen contains 63.1% oxygen and has a molar mass of 76.0 g/mol. What is the molecular formula for this compound

Solution

Taking $O=15.9994\quad N=14.0067$

Mass of Oxygen in $100g$ sample $= \frac{63.1}{100}×100=63.1g$

Number of moles of Oxygen $=\frac{63.1}{15.9994}=3.9439Moles$

$\%$ of Nitrogen $=(100-63.1)$

$=36.9\%$

Mass of Nitrogen in 100g sample $=\frac{36.1}{100}×100=36.1g$

Number of moles of Nitrogen $=\frac{36.9}{14.0067}=2.6345moles$

Moles ratio $N:O=2.6345: 3.9439$

Dividing by smaller number of moles $N:O=1.4970$

Multiplying by 2 and taking integral values

$N:O=2:3$

Empirical formula is $N_2O_3$

Molar mass of $N_2O_3=(14.0067×2)+(15.9994×3)$

$=76.0116g$

Relative Molecular Mass $=76$ g/mole

Molecular formula $=N_2O_3$