Chemistry Stoichiometry PMDC 2020
PMDC Verified Question 68 of 105
The efficiency of a chemical reaction can be expressed as:
A
Theoretical yield
B
Actual yield
C
% yield
D
Maximum yield
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: % yield
Concept:

In industrial and laboratory chemistry, efficiency measures how successfully the reactants were converted into the desired product compared to the ideal, lossless scenario.

Formula:

$$ \% \text{ yield} = \left( \frac{\text{Actual yield}}{\text{Theoretical yield}} \right) \times 100 $$

Solution:

  • Theoretical yield is just a calculated ideal on paper. It assumes a flawless 100% conversion with zero mechanical loss.


  • Actual yield is merely the raw mass obtained, which lacks context on its own.


  • Percentage yield (% yield) combines both. It acts as a standardized metric (from 0% to 100%) that definitively expresses the true efficiency of a chemical process.


Why other options are incorrect:

  • Theoretical/Maximum yield: A perfectly calculated ceiling, but says nothing about how well the real-world reaction actually performed.


  • Actual yield: A raw number (e.g., "We got 15 grams"). Without comparing it to the theoretical yield, you have no idea if 15 grams is highly efficient or a catastrophic failure.

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