Consider the following reaction : x AsjSg + yOj —) z AS2O3 + wS02 What is y {the coefficient for 02) when this equation is balanced using whole number coefficients?

To balance the chemical equation x As2S3 + y O2 → z As2O3 + w SO2, we must ensure the number of atoms for each element is equal on both sides. Starting with arsenic (As), there are 2 atoms on the left, so z must be 1 if x is 1. For sulfur (S), there are 3 atoms on the left, requiring w to be 3 to provide 3 sulfur atoms in SO2. Counting the oxygen atoms on the product side, As2O3 contributes 3 atoms and 3 SO2 molecules contribute 6 atoms (3 × 2), totaling 9 oxygen atoms. Since oxygen exists as O2 on the reactant side, we need 4.5 molecules of O2 to get 9 atoms. To achieve the smallest whole-number coefficients, we multiply the entire equation by 2, resulting in 2 As2S3 + 9 O2 → 2 As2O3 + 6 SO2. Thus, the coefficient y for O2 is 9.