Azobenzene is a highly colored organic compound. Many diazo dyes used in coloring of clothing are based on an azobenzene core. The elemental analysis of azobenzene provides 79.10% carbon, 5.53% hydrogen, and the rest is nitrogen. It has a molar mass of 182.23 g/mol. What is the molecular formula of azobenzene?

Question

Quizplus · Accepted Answer

The percentages of carbon and hydrogen in the compound suggest the presence of 12 carbon and 12 hydrogen atoms, respectively. The molar mass of 182.23 g/mol suggests that the molecular formula contains multiple units of the empirical formula. To determine the number of nitrogen atoms, we subtract the mass contributed by carbon and hydrogen from the molar mass - this gives us the mass contributed by nitrogen to be 45.64 g/mol. Dividing this mass by the molar mass of nitrogen (14.01 g/mol) gives us approximately 3.26. Therefore, the molecular formula contains 3 units of the empirical formula, C6H5N=NC6H5, which corresponds to choice B.

Azobenzene Is a Highly Colored Organic Compound