When balancing the reaction involving SO2 and O2, how many moles of SO2 are needed for 1 mole of O2?

• A. 0.5 mol
• B. 2 mol
• C. 3 mol
• D. 4 mol

Answer: (B)

In the reaction between sulfur dioxide (SO2) and oxygen (O2), the balanced chemical equation is essential to determine the stoichiometric ratios of the reactants. The reaction can be represented as:

[ \text{2 SO}_2 + \text{O}_2 \rightarrow \text{2 SO}_3 ]

From this balanced equation, it can be observed that for every 1 mole of O2 consumed, 2 moles of SO2 are required to produce sulfur trioxide (SO3). This stoichiometric relationship indicates that the reactants must be combined in specific ratios to ensure that the reaction proceeds correctly and to maximize product formation.

Thus, to find how many moles of SO2 are needed for 1 mole of O2, one can simply refer to the coefficients in the balanced equation. The coefficient for SO2 is 2, whereas the coefficient for O2 is 1. Therefore, 2 moles of SO2 are necessary for every 1 mole of O2, which supports the assertion that the correct answer is 2 moles.