Question

If 4.04 g of nitrogen combine with 11.46 g of oxygen to produce a compound with a molar mass of 108.0 g. What is the molecular formula of this compound?

Answer 1

The molecular formula of the compound formed by nitrogen and oxygen, with a molar mass of 108.0 g, is determined to be
`N_2O_5`based on the mole ratio of the elements and the given molar mass.

Step-by-step explanation:

To determine the molecular formula of the compound formed by nitrogen and oxygen, we start by finding the mole ratio of the elements based on their weights and atomic masses. Nitrogen has an atomic mass of 14 g/mol, and oxygen has an atomic mass of 16 g/mol.

Therefore, 4.04 g of nitrogen is equivalent to 4.04 g / 14 g/mol = 0.289 mol of nitrogen.

For oxygen, 11.46 g corresponds to 11.46 g / 16 g/mol = 0.71625 mol of oxygen.

The simplest mole ratio of nitrogen to oxygen can be found by dividing each by the smaller amount: 0.289 mol N / 0.289 = 1 and 0.71625 mol O / 0.289 = 2.48.

This suggests the empirical formula of the compound is approximately N1O2.5. However, since we cannot have half an atom in a chemical formula, we must multiply each subscript in the empirical formula by 2 to obtain whole numbers, resulting in a tentative empirical formula of
`N_2O_5`.

Given the molar mass of 108.0 g, we divide this by the molar mass of the empirical formula to find the number of empirical units in the molecular formula. The molar mass of N2O5 (atomic masses: 2×14 for N and 5×16 for O) is 2(14) + 5(16) = 108 g/mol, which matches the given molar mass. This confirms that the molecular formula of the compound is indeed
`N_2O_5`.