Chemistry Reaction Kinetics MDCAT 2013
PMDC Verified Question 74 of 80
In zero order reaction, the rate is independent of:
A
Concentration of the product
B
Temperature of the reaction
C
Surface area of the product
D
Concentration of the reactant
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Concentration of the reactant
Concept:

The defining characteristic of a zero-order reaction is that its rate does not change as the reactant concentration changes.

Formula:

$$ \text{Rate} = k[\text{A}]^{0} = k $$

Solution:

  • In a rate law expression for a zero-order reaction, the sum of the exponents of the concentration terms is zero.
  • Any value raised to the power of zero is 1. Therefore, the rate equals the rate constant (\( k \)).
  • This means the rate is completely independent of the concentration of the reactant(s).


Why other options are incorrect:

Rate is always independent of product concentration in standard initial rate laws. However, the specific hallmark defining 'zero order' is its independence from the reactant concentration. Temperature always affects the rate constant \( k \).

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