Question

a compound consists of 17.6% of hydrogen and 82.4% nitrogen. Determine the empirical formula of the compound

Answer 1

Answer on Question #44029, Chemistry, Other

Question:

A compound consists of 17.6% of hydrogen and 82.4% nitrogen. Determine the empirical formula of the compound.

Solution:

Let's assume that we have 100 g of the compound. From the given mass percents of the elements in the compound, we can determine the mass of the elements:

$$\text{mass of element} = (\text{mass of compound}) \times (\text{mass percents of element}) / 100\%,$$ $$\begin{array}{l} m(H) = 100 \, \text{g} \times 17.6\% / 100\% = 17.6 \, \text{g} \\ m(N) = 100 \, \text{g} \times 82.4\% / 100\% = 82.4 \, \text{g} \end{array}$$

This means, we have 17.6 g of hydrogen and 82.4 g of nitrogen.

We can convert each mass to moles using the molar mass of the element (from the periodic table):

$$17.6 \, \text{g} / (1 \, \text{g/mol}) = 17.6 \, \text{mol of H},$$ $$82.4 \, \text{g} / (14 \, \text{g/mol}) = 5.89 \, \text{mol of N}.$$

We can find the lowest whole-number ratio of the elements in the compound:

$$\text{the lowest whole number ratio} = (\text{molar amount}) / (\text{lowest molar amount})$$ $$N/H = 5.89 / 17.6 \, (\text{divide each of the found values by 5.89}),$$ $$N/H = 1 / 2.99 \approx 1 / 3.$$

The empirical formula of the compound is $N_1H_3$ or $NH_3$.

Answer: The empirical formula of the compound is $NH_3$.

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