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Question #44833

Difficulty: 8/10 | 🟢 Free

The Question

Consider the hydrolysis of an ester catalyzed by a typical mesophilic enzyme (optimum temperature Topt=310T_{opt} = 310 K). At 293293 K, the reaction proceeds with an initial rate v0=2.5×10−4v_0 = 2.5 \times 10^{-4} mol L−1^{-1} s−1^{-1}. The temperature coefficient Q10Q_{10} is determined to be 2.02.0 in the range of 283283 K to 303303 K. A theoretical kineticist calculates the expected rate vcalcv_{calc} at 333333 K using the Q10Q_{10} rule. Assuming the uncatalyzed reaction rate is negligible, what are the values of the calculated rate (vcalcv_{calc}) and the experimentally observed rate (vobsv_{obs}) at 333333 K, respectively?

Options

  • A.

    4.0×10−34.0 \times 10^{-3} mol L−1^{-1} s−1^{-1} and ≈0\approx 0

  • B.

    4.0×10−34.0 \times 10^{-3} mol L−1^{-1} s−1^{-1} and 4.0×10−34.0 \times 10^{-3} mol L−1^{-1} s−1^{-1}

  • C.

    2.0×10−32.0 \times 10^{-3} mol L−1^{-1} s−1^{-1} and ≈0\approx 0

  • D.

    1.0×10−31.0 \times 10^{-3} mol L−1^{-1} s−1^{-1} and 1.0×10−31.0 \times 10^{-3} mol L−1^{-1} s−1^{-1}

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

Temperature Coefficient (Q10)|Enzyme Specificity 'Lock and Key'

Why This Question Is Tricky

Common Mistakes

This problem tests the boundary conditions of mathematical models in physical chemistry.

Students often blindly apply the Arrhenius equation or the Q10Q_{10} temperature coefficient rule to calculate reaction rates at elevated temperatures.

The 'Hidden Variable' here is the physical integrity of the catalyst itself.

Because the catalyst is a protein (enzyme) with a specific optimum temperature (310310 K), extrapolating the kinetic model to 333333 K ignores the thermal denaturation of the enzyme.

The trap distinguishes students who merely plug numbers into formulas from those who understand the physical and biochemical reality of the reaction system.

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterChemical Kinetics - Class 12
ConceptTemperature Coefficient (Q10)
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree