Concept:Theoretical yield assumes a flawless, 100% efficient reaction environment. Real-world actual yields are universally lower due to a host of physical and chemical imperfections.
Formula:$$ \text{Actual Yield} = \text{Theoretical Yield} - \text{Losses} $$
Solution:- The question asks for the incorrect reason (i.e., which statement does NOT cause a low actual yield).
- If a substance is completely pure, it actually behaves exactly as stoichiometry predicts, maximizing the yield toward the theoretical limit.
- Therefore, substance purity is a positive factor, not a cause for the actual yield being less than expected. (Impure reactants, conversely, DO lower yield).
Why other options are incorrect:- Mechanical losses: Spilling, filtering, and transferring chemicals physically lose mass, directly lowering actual yield.
- Reversibility: Reversible reactions reach equilibrium before 100% of reactants are consumed, lowering yield.
- Activation energy: If molecules lack activation energy, they collide without reacting, resulting in incomplete conversion and lowering yield.
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