Question

A sample of an unknown compound was analyzed using elemental analysis, and the results showed that the compound contains 12.8% hydrogen, 49.2% carbon, and 38.0% oxygen by mass. What is the empirical formula of the compound?

Answer 1

To determine the empirical formula of the compound, we will follow these steps:1. Assume we have 100 g of the compound. This way, the percentages can be treated as grams.2. Convert the grams of each element to moles.3. Divide the moles of each element by the smallest number of moles to get the mole ratio.4. If necessary, round the mole ratio to the nearest whole number to get the empirical formula.Step 1: Assume 100 g of the compound- Hydrogen: 12.8 g- Carbon: 49.2 g- Oxygen: 38.0 gStep 2: Convert grams to moles- Hydrogen: 12.8 g /  1.008 g/mol  = 12.7 mol- Carbon: 49.2 g /  12.01 g/mol  = 4.1 mol- Oxygen: 38.0 g /  16.00 g/mol  = 2.375 molStep 3: Divide by the smallest number of moles  2.375 - Hydrogen: 12.7 mol / 2.375 = 5.35  5- Carbon: 4.1 mol / 2.375 = 1.73  2- Oxygen: 2.375 mol / 2.375 = 1Step 4: The empirical formula is C2H5O.