Question

Calculate the empirical formula of a compound that contains 67.9% carbon, 5.7 % H and 26.4 % N. When entering the formula place in the following order: carbon, hydrogen, nitrogen.

Answer 1

Answer:

$C_3H_3N$

Explanation:

Hello!

In this case, for this percent composition problem, we can start assuming that the given percentages are actually the mass of each atom in the sample, se we can compute the moles of each one as shown below:

$n_C=67.9gC*\frac{1molC}{12gC}=5.66molC\\ \\n_H=5.7gH*\frac{1molH}{1gH}=5.7molH \\\\n_N=26.4gN*\frac{1molN}{14gN}=1.89N$

Next, we can find the subscript of each element in the empirical formula by diving the resulting moles by the smallest moles, in this case, moles of nitrogen:

$C:\frac{5.66}{1.89}=3.0\\ \\H:\frac{5.7}{1.89}=3.0\\ \\N:\frac{1.89}{1.89}=1$

It means that the empirical formula is:

$C_3H_3N$

Best regards!