1. A 7.546 g sample of an unknown compound was analyzed and found to contain only nitrogen and oxygen. If the mass of nitrogen present in the sample was 1.957 g, determine the empirical formula
of the compound

N₂O₅

Explanation:

From the question given above, the following data were obtained:

Mass of compound = 7.546 g

Mass of nitrogen (N) = 1.957 g

Empirical formula =?

Next, we shall determine the mass of oxygen present in the compound. This can be obtained as follow:

Mass of compound = 7.546 g

Mass of nitrogen (N) = 1.957 g

Mass of Oxygen (O) =?

Mass of O = (Mass of compound) – (Mass of N)

Mass of O = 7.546 – 1.957

Mass of O = 5.589 g

Finally, we shall determine the empirical formula of the compound. This can be obtained as follow:

Mass of nitrogen (N) = 1.957 g

Mass of oxygen (O) = 5.589 g

Divide by their molar mass

N = 1.957 / 14 = 0.14

O = 5.589 / 16 = 0.35

Divide by the smallest

N = 0.140 / 0.14 = 1

O = 0.35 / 0.14 = 2.5

Multiply through by 2 to express in whole number

N = 1 × 2 = 2

O = 2.5 × 2 = 5

The empirical formula of the compound is N₂O₅.

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