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A pure sample of a compound is found to contain 1.11x1022 nitrogen atoms of and 2.22x1022 oxygen atoms. What is the empirical formula of the compound?

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The empirical formula of the compound is NO₂

calculation

Step 1: find the moles of Nitrogen and oxygen using the Avogadro's law constant

That is according to Avogadro's law 1 mole = 6.02 x 10²³ atoms

The moles of nitrogen (N) is calculated as below

= 1 mole = 6.02 x 10²³ atoms

? moles= 1.11 x 10²² atoms

by cross multiplication

= {(1 mole x 1.11 x10²² atoms) / 6.02 x 10²³ atoms} = 0.0184 moles


moles of oxygen is calculated as below

1 mole = 6.02 x 10 ²³ atoms

? moles= 2.22 x 10²² atoms

by cross multiplication

={ (1 mole x 2.22 x 10²² atoms) / 6.02 x 10²³} = 0.0369 moles


Step 2: find the mole ratio of N to O by dividing each mole by smallest number of mole (0.0184)

That is;

for N = 0.0184 /0.0184 = 1

for O =0.0369/0.0184 =2

Therefore the empirical formula = NO₂

User Leonardo Rignanese
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