The hydrolysis of an ester is studied under identical conditions in four separate trials

CHEMISTRY · Subjective · A Level · Chemistry · Kinetics · Kinetics

Problem

The hydrolysis of an ester is studied under identical conditions in four separate trials. 1. No additive: initial rate = 1.8×10−4 M s−11.8\times10^{-4}\,\text{M}\,\text{s}^{-1} 2. Added 0.010 M0.010\,\text{M} HCl: initial rate = 1.8×10−4 M s−11.8\times10^{-4}\,\text{M}\,\text{s}^{-1} 3. Added 0.0020 M0.0020\,\text{M} pyridine: initial rate = 5.4×10−5 M s−15.4\times10^{-5}\,\text{M}\,\text{s}^{-1} 4. Added 5 mg of enzyme E: initial rate = 9.0×10−3 M s−19.0\times10^{-3}\,\text{M}\,\text{s}^{-1}; mass of E is unchanged after the reaction. Identify which additive acts as a catalyst and which additive acts as an inhibitor, and justify your choices in one sentence.

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