Multiple Choice
Upon combustion, a 0.8009 g sample of a compound containing only carbon, hydrogen, and oxygen produces 1.6004 g CO2 and 0.6551 g H2O. What is the empirical formula of the compound?
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3. Chemical Reactions
Empirical Formula
Multiple Choice
A 4.386 g compound of hydrogen, carbon, and oxygen was burned in 9.389 g of oxygen, producing 6.184 g of carbon dioxide and 3.789 g of water. What is the empirical formula of the original sample?
A
C2H6O
B
CH2O
C
C3H6O2
D
C2H4O
Verified step by step guidance1
Determine the mass of carbon in the carbon dioxide produced. Use the molar mass of CO2 (44.01 g/mol) and the fact that each mole of CO2 contains one mole of carbon (12.01 g/mol). Calculate the moles of CO2 and then the mass of carbon: \( \text{mass of carbon} = \frac{6.184 \text{ g CO}_2}{44.01 \text{ g/mol}} \times 12.01 \text{ g/mol} \).
Determine the mass of hydrogen in the water produced. Use the molar mass of H2O (18.02 g/mol) and the fact that each mole of H2O contains two moles of hydrogen (2.02 g/mol). Calculate the moles of H2O and then the mass of hydrogen: \( \text{mass of hydrogen} = \frac{3.789 \text{ g H}_2\text{O}}{18.02 \text{ g/mol}} \times 2.02 \text{ g/mol} \).
Calculate the mass of oxygen in the original compound. Subtract the mass of carbon and hydrogen from the total mass of the compound: \( \text{mass of oxygen} = 4.386 \text{ g} - (\text{mass of carbon} + \text{mass of hydrogen}) \).
Convert the masses of carbon, hydrogen, and oxygen to moles by dividing each by their respective atomic masses: \( \text{moles of C} = \frac{\text{mass of carbon}}{12.01 \text{ g/mol}} \), \( \text{moles of H} = \frac{\text{mass of hydrogen}}{1.008 \text{ g/mol}} \), \( \text{moles of O} = \frac{\text{mass of oxygen}}{16.00 \text{ g/mol}} \).
Determine the empirical formula by finding the simplest whole number ratio of moles of carbon, hydrogen, and oxygen. Divide each mole value by the smallest number of moles calculated in the previous step. Adjust the ratios to the nearest whole numbers to find the empirical formula.
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