A compound contains 40.0% carbon 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula. [H = 1, C = 12, O = 1...
A compound contains 40.0% carbon 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula.
[H = 1, C = 12, O = 16]
Answer Details
The compound is made up of 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen. We need to find the molecular formula of the compound. The first step is to calculate the empirical formula by converting the percentages to mole ratios.
To do this, we assume that we have 100 grams of the compound, so we have 40.0 grams of carbon, 6.7 grams of hydrogen, and 53.3 grams of oxygen. Then we convert each of these masses to moles using their respective molar masses:
- Carbon: 40.0 g * (1 mol / 12.0 g) = 3.33 mol
- Hydrogen: 6.7 g * (1 mol / 1.0 g) = 6.7 mol
- Oxygen: 53.3 g * (1 mol / 16.0 g) = 3.33 mol
Next, we divide each of these mole values by the smallest of the three, which is 3.33 mol:
- Carbon: 3.33 mol / 3.33 mol = 1
- Hydrogen: 6.7 mol / 3.33 mol ≈ 2
- Oxygen: 3.33 mol / 3.33 mol = 1
This gives us an empirical formula of CH2O.
To find the molecular formula, we need to know the actual molar mass of the compound. The problem states that the molar mass is 180 g/mol. To find the molecular formula, we divide the molar mass by the empirical formula mass:
- Empirical formula mass: 12.0 g/mol (C) + 2.0 g/mol (H) + 16.0 g/mol (O) = 30.0 g/mol
- Molecular formula mass: 180 g/mol / 30.0 g/mol = 6
So the molecular formula is some multiple of the empirical formula. From the options provided, we can see that has the correct ratio of atoms: C6H12O6. Therefore, the molecular formula of the compound is C6H12O6.