Which plot of ln k vs 1/T is consistent with Arrhenius equation?
Correct Answer :
Solution :
The Arrhenius equation relates the rate constant, activation energy, and temperature of a chemical reaction, and is given by:
Where:
- is the rate constant,
- is the pre-exponential factor (Arrhenius constant),
- is the activation energy,
- is the universal gas constant, and
- is the absolute temperature (in Kelvin).
Taking the natural logarithm () on both sides of the equation:
Using the properties of logarithms, this simplifies to:
Rearranging the terms to fit the slope-intercept form of a straight line ():
Comparing this with where we plot on the vertical axis and on the horizontal axis:
- The slope () is .
- The y-intercept () is .
Since activation energy () and the gas constant () are positive quantities, the slope of the line must be negative (). Therefore, the plot of versus is a straight line with a negative slope.
By analyzing the provided images:
- The first image shows a straight line with a positive slope starting below the origin.
- The second image shows a straight line with a positive slope starting above the origin.
- The third image shows a straight line with a positive slope passing through the origin.
- The fourth image shows a straight line with a negative slope and a positive y-intercept.
Thus, the fourth plot is the one consistent with the Arrhenius equation.
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