Understanding Arrhenius Plots: ln(rate) vs 1/T for Determining Activation Energy

T to find activation energy in certain cases. It is because the Arrhenius law states that the rate constant, k, is equal to A*exp(-Ea/(R*T)). This allows us to manipulate the equation to ln(rate) vs 1/T, which can also be used to determine the activation energy in heterogeneous catalysis. Additionally, some people may refer to the rate constant as simply "rate," but the equation still applies as long as the rate is constant. In summary, in certain cases, the Arrhenius plot can be manipulated to ln(rate) vs 1/T to find activation energy in heterogeneous catalysis, as the Arrhenius law
  • #1
pwnzorz
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I have been noticing that in some cases that Arrhenius plots are sometimes plotted ln(rate) vs 1/T as opposed to ln(k) vs 1/T to find activation energy especially in hetereogeneous catalysis.

Isn't the Arrhenius law k=A*exp(-Ea/(R*T))? why can ln(rate) also be plotted vs T^-1 to find activation energy?
 
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  • #2
pwnzorz said:
I have been noticing that in some cases that Arrhenius plots are sometimes plotted ln(rate) vs 1/T as opposed to ln(k) vs 1/T to find activation energy especially in hetereogeneous catalysis.

Isn't the Arrhenius law k=A*exp(-Ea/(R*T))? why can ln(rate) also be plotted vs T^-1 to find activation energy?
Is it possible that some people refer to the rate constant simply as "rate?" Otherwise, the rate would have to be constant for the equation to apply.

Chet
 

FAQ: Understanding Arrhenius Plots: ln(rate) vs 1/T for Determining Activation Energy

What is an Arrhenius plot?

An Arrhenius plot is a graphical representation of the Arrhenius equation, which describes the relationship between the rate of a chemical reaction and the temperature at which it occurs. It is used to determine the activation energy of a reaction.

How do I construct an Arrhenius plot?

To construct an Arrhenius plot, you will need to collect data on the rate of the reaction at different temperatures. Plot the natural logarithm of the rate (ln(k)) on the y-axis and the reciprocal of the temperature (1/T) on the x-axis. The slope of the resulting line is equal to the negative activation energy.

What is the significance of the activation energy in an Arrhenius plot?

The activation energy is a measure of the minimum amount of energy required for a chemical reaction to occur. In an Arrhenius plot, it is represented by the slope of the line and can provide valuable information about the mechanism of the reaction and the stability of the reactants and products.

Can an Arrhenius plot be used for any type of reaction?

An Arrhenius plot is typically used for reactions that follow the Arrhenius equation, which describes the effect of temperature on the rate of a reaction. However, it may not be applicable for reactions with complex mechanisms or those that do not exhibit a clear temperature dependence.

How can I use an Arrhenius plot to determine the rate constant of a reaction?

To determine the rate constant (k) of a reaction from an Arrhenius plot, you can use the slope-intercept form of the equation: ln(k) = -Ea/R + ln(A), where Ea is the activation energy, R is the gas constant, and A is the pre-exponential factor. The value of k can be calculated using the slope and intercept of the line.

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