Concept:Using the molar ratios established by the balanced chemical equation, we can directly convert the moles of a decomposed reactant into the moles of generated product.
Formula:$$ \frac{\text{Moles of O}_2}{\text{Coefficient of O}_2} = \frac{\text{Moles of KClO}_3}{\text{Coefficient of KClO}_3} $$
Solution:- The balanced equation establishes the molar ratio: 2 moles of \( \text{KClO}_3 \) decompose to produce exactly 3 moles of \( \text{O}_2 \).
- We are provided with 12 moles of \( \text{KClO}_3 \).
- Let \( x \) be the moles of \( \text{O}_2 \) produced. Set up a cross-multiplication:
\( \frac{2}{12} = \frac{3}{x} \)
- \( 2x = 36 \)
- \( x = 18 \text{ moles of O}_2 \).
Why other options are incorrect:- 12 moles: Assumes an incorrect 1:1 molar ratio, ignoring the coefficients entirely.
- 15 & 21 moles: Random arithmetic outputs that do not align with the strict 2:3 reaction stoichiometry.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.