Find the empirical Formula of a compound that is 30.4% nitrogen by mass, and consists of only nitrogen and oxygen. What is its molecular formula if its molar mass is 92g/mol?
To find the empirical formula of the compound, we need to determine the ratio of atoms of each element present.
1. Start by assuming we have 100 grams of the compound. Since it is 30.4% nitrogen by mass, we have 30.4 grams of nitrogen.
2. Next, calculate the mass of oxygen by subtracting the mass of nitrogen from the total mass of the compound:
Total mass - mass of nitrogen = mass of oxygen
100 g - 30.4 g = 69.6 g
3. Now, we need to convert the masses of nitrogen and oxygen into moles by using their respective atomic masses.
The atomic mass of nitrogen (N) is 14.01 g/mol, and the atomic mass of oxygen (O) is 16.00 g/mol.
Moles of nitrogen = mass of nitrogen / atomic mass of nitrogen
Moles of nitrogen = 30.4 g / 14.01 g/mol ≈ 2.171 mol
Moles of oxygen = mass of oxygen / atomic mass of oxygen
Moles of oxygen = 69.6 g / 16.00 g/mol ≈ 4.350 mol
4. To find the mole ratio between nitrogen and oxygen, divide the number of moles of each element by the smallest number of moles.
Nitrogen ratio = 2.171 mol / 2.171 mol ≈ 1
Oxygen ratio = 4.350 mol / 2.171 mol ≈ 2
5. Finally, we have the empirical formula of the compound, which is N1O2.
To determine the molecular formula, we need to know the molar mass of the empirical formula. The molar mass of N1O2 is:
(1 * 14.01 g/mol) + (2 * 16.00 g/mol) = 46.01 g/mol
To find the molecular formula, divide the given molar mass of the compound by the molar mass of the empirical formula:
Molecular formula ratio = molar mass of the compound / molar mass of the empirical formula
Molecular formula ratio = 92 g/mol / 46.01 g/mol ≈ 2
Therefore, the molecular formula of the compound is 2(N1O2), which simplifies to N2O4.