Combustion of a 0.9835-g sample of a compound containing only carbon, hydrogen, and oxygen produced 1.900 g of CO₂ and 1.070 g of H₂O. What is the empirical formula of the compound? A)C₂ H₅O B)C₄ H₁₀O₂ C)C₄ H₁₁O₂ D)C₄ H₁₀O E)C₂ H₅O₂

Question

Quizplus · Accepted Answer

First, we need to find the moles of each product using their molar masses: 
moles of COS: 1.900 g / 60.07 g/mol = 0.03163 mol 
moles of H2O: 1.070 g / 18.02 g/mol = 0.05935 mol

Next, we need to find the moles of carbon, hydrogen, and oxygen in the original sample: 
moles of carbon = moles of COS = 0.03163 mol 
moles of hydrogen = 2 x moles of H2O = 0.1187 mol 
moles of oxygen = (moles of COS1U1B12S1U1B0 x 2) + (moles of H2O x 1) - moles of sample 
moles of oxygen = (0.03163 x 2) + (0.05935 x 1) - (0.9835 / 44.01) = 0.03947 mol

Finally, we need to find the empirical formula by dividing each mole value by the smallest mole value: 
empirical formula = C1.41H4.99O1 
We can round to the nearest whole number to get the final answer of: 
empirical formula = C1U1B14S1U1B0 H5O