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MDCAT Chemistry QUESTION #4354
Question 1
Consider the balanced chemical equation: $2H_2 + O_2 \rightarrow 2H_2O$. If $4\ g$ of $H_2$ reacts with $32\ g$ of $O_2$ to produce $28\ g$ of $H_2O$, what is the percentage yield of the reaction? (Molar mass of $H_2 = 2\ g/mol$, $O_2 = 32\ g/mol$, $H_2O = 18\ g/mol$)
  • 63.6%
  • 77.8%✔️
  • 87.5%
  • 92.5%
Correct Answer Explanation
Moles of $H_2 = \frac{4}{2} = 2\ mol$. Theoretical yield of $H_2O = 2 \times 18 = 36\ g$. $\% yield = \frac{28}{36} \times 100 = 77.8\%$.