Chemistry Reaction Kinetics MDCAT 2017
PMDC Verified Question 66 of 80
Rate of first order reaction depends on:
A
Independence of the initial concentration
B
Concentration of one reactant
C
Concentration of two reactants
D
Concentration of three reactants
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Concentration of one reactant
Concept:

The order of a reaction dictates how the reaction rate scales with the concentration of its reactants.

Formula:

$$ \text{Rate} = k[\text{A}]^{1} $$

Solution:

  • By definition, a first-order reaction has a rate law where the sum of the exponents of concentration terms is equal to 1.
  • This means the rate depends strictly on the first power of the concentration of a single reacting species.


Why other options are incorrect:

Dependence on two or three reactants implies second or third-order kinetics, respectively. The rate (not half-life) is highly dependent on the initial concentration.

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