Chemistry
Chemistry
Problem
Combustion of a 0.450 g sample of an unknown compound that contains only C, H, and O produces 1.10 g CO₂ and 0.450 g H₂O. What is the empirical formula of the compound? a) C₃H₆O b) C₄H₈O c) C₄H₄O d) C₂H₄O₂Intuitive explanation
The key is to reverse-engineer the original compound from its combustion products. All the carbon atoms in the sample ended up in CO₂, and all the hydrogen atoms ended up in H₂O, so you can work backward: find moles of C from the CO₂, moles of H from the H₂O, then find moles of O by subtraction. Once you have mole counts, divide by the smallest to get the simplest whole-number ratio—that's your empirical formula.
Intuitive explanation
The key is to reverse-engineer the original compound from its combustion products. All the carbon atoms in the sample ended up in CO₂, and all the hydrogen atoms ended up in H₂O, so you can work backward: find moles of C from the CO₂, moles of H from the H₂O, then find moles of O by subtraction. Once you have mole counts, divide by the smallest to get the simplest whole-number ratio—that's your empirical formula.