Question

A sample of N2O4 contains 1.24 moles of nitrogen. Use the following atomic masses: N =14, O=16.

The number of moles of N2O4 present = mol

N2O4 The mass of the sample = g

N2O4 The number of moles of oxygen in the sample = mol

O The mass of oxygen in the sample = g O

Answer 1

N2O4 ; 1 mole N2O4 has 2 mole N atoms and 4 mol O atoms
when 1.24 mol N atom present

mols of N2O4 = [1 mole N2O4 / 2mol N atoms]*1.24 mol N atoms
= 0.62 mols N2O4
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1 mol N2O4 has mass= molar mass= 2* 14 + 4*16
=92 g/mol

so mass of 0.62 mol N2O4 = 0.62 mol * 92 g/mol = 57.04 g
mass of N2O4 = 57.0 g
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1 mol N2O4 contain 4 mol O atoms
0.62 mol = 4* 0.62 mol = 2.48 mol

mols of O atoms = 2.48 mols
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mass of O atoms in the sample = 16 g/mol * 2.48 mol = 39.68 g

Mass of O atoms = 39.7 g
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