The odor of pineapple is due to the compound ethyl butyrate, which contains hydrogen, carbon, and oxygen. When 3.70g of ethyl butyrate are burned, 8.41g of carbon dioxide and 3.43g of water are the only products. Determine the empirical formula of ethyl butyrate.
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To determine the empirical formula of ethyl butyrate, we need to find the ratio of atoms present in the compound. Here's how we can calculate it:
Step 1: Find the moles of carbon dioxide (CO2) and water (H2O) produced.
To do this, we divide the given masses of CO2 and H2O by their respective molar masses.
Molar mass of CO2:
C = 12.01 g/mol, O = 16.00 g/mol (2 atoms in CO2)
Total molar mass of CO2 = 12.01 + (2 * 16.00) = 44.01 g/mol
Moles of CO2 = mass of CO2 / molar mass of CO2 = 8.41 g / 44.01 g/mol = 0.1910 mol
Molar mass of H2O:
H = 1.01 g/mol (2 atoms in H2O), O = 16.00 g/mol
Total molar mass of H2O = (2 * 1.01) + 16.00 = 18.02 g/mol
Moles of H2O = mass of H2O / molar mass of H2O = 3.43 g / 18.02 g/mol = 0.1906 mol
Step 2: Find the moles of carbon, hydrogen, and oxygen in the ethyl butyrate.
The total moles of carbon, hydrogen, and oxygen in the ethyl butyrate are equal to the moles found in the CO2 and H2O.
Carbon: Since there is only carbon in CO2, the moles of carbon are the same as the moles of CO2, i.e., 0.1910 mol.
Hydrogen: Since there are two hydrogen atoms in each molecule of H2O, we need to double the moles of H2O. Therefore, the moles of hydrogen are 2 * 0.1906 mol = 0.3812 mol.
Oxygen: There is no direct source of oxygen in the problem except for the one oxygen atom in each molecule of CO2. Therefore, the moles of oxygen are the same as the moles of CO2, i.e., 0.1910 mol.
Step 3: Simplify the mole ratio by dividing by the smallest value.
Dividing each mole value by 0.1910 (the smallest value) gives:
Carbon: 0.1910 mol / 0.1910 = 1
Hydrogen: 0.3812 mol / 0.1910 = 2
Oxygen: 0.1910 mol / 0.1910 = 1
Step 4: Write the empirical formula using the mole ratio.
From the simplification above, we find that the empirical formula of ethyl butyrate is C1H2O1, which can be simplified to CH2O.
Therefore, the empirical formula of ethyl butyrate is CH2O.