Ch.13 - Chemical KineticsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: The accompanying graph shows plots of ln k versus 1/T for two different reactions. The plots have been extrapolated to the y-intercepts. Which reaction has the larger value for the frequency factor, A

Solution: The accompanying graph shows plots of ln k versus 1/T for two different reactions. The plots have been extrapolated to the y-intercepts. Which reaction has the larger value for the frequency factor, A

Problem

The accompanying graph shows plots of ln k versus 1/T for two different reactions. The plots have been extrapolated to the y-intercepts. 

A graph of natural log k versus 1 divided by T (both unscaled) shows a red and blue line that both decline linearly. The red line starts higher on the y-axis and its slope is flatter.

Which reaction has the larger value for the frequency factor, A?

Solution

In the problem, we are asked to find which of the two plots has a larger value for the frequency factor (A).


The Arrhenius Equation shows the dependence of the rate constant on the pre-exponential factor, absolute temperature and activation energy of the reaction

Mathematically, the Arrhenius Equation is expressed as:

k=Ae-EaRT

Where:
             k is the rate constant
             A is the frequency factor
             Ea is the activation energy
             R is the gas constant (8.314 J/mol•K )
             T is the temperature

To solve this problem we must relate the Arrhenius Equation to the plot of the graph.


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