Calculating Activation Energy Using Slope and the Arhennius Equation

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In summary, the conversation is about the Arhennius equation and how to calculate it using tables of temperature and k. The equation can be linearized using the natural logarithm and the slope of the resulting line represents the activation energy. It is important to note that the slope must be multiplied by the gas constant to get the actual value of the activation energy.
  • #1
relativitydude
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For some reason, this isn't working out.

The Arhennius equation, k = A*e^(-Ea/RT)

I have tables of temperature and k. The book says just calculate it by having the x-axis be 1/T and y-axis be ln(k)

Ok, take Ln of both sides
ln(k) = ln(A*e^(-Ea/RT))
ln(k) = -Ea/RT + ln(A)

Oh, that looks like y = mx + b
 
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  • #2
So there's actually no problem.It's a standard way of linearizing exponential laws...

Daniel.
 
  • #3
Ya, I was just being stupid.
 
  • #4
Note that Ea will be the absolute value of the slope. The slope will be negative, Ea must be positive.
 
  • #5
Gokul,if you wanted to be strict,u should have mentioned that Ea is the absolute value of the slope TIMES THE GAS CONSTANT "R"...

Daniel.
 
  • #6
dextercioby said:
Gokul,if you wanted to be strict,u should have mentioned that Ea is the absolute value of the slope TIMES THE GAS CONSTANT "R"...

Daniel.

I should have.

It's common to make the x-axis 1/RT or [itex]\beta[/itex] (when dealing with numbers instead of moles).
 

Related to Calculating Activation Energy Using Slope and the Arhennius Equation

1. What is the purpose of calculating Ea through slope?

The purpose of calculating Ea (activation energy) through slope is to determine the energy required for a chemical reaction to occur. It helps scientists understand the rate at which reactions take place and can provide valuable information for optimizing reaction conditions.

2. How is Ea calculated using slope?

Ea can be calculated using the Arrhenius equation, which relates the rate constant of a reaction to its temperature. By plotting the natural logarithm of the rate constant against the inverse of temperature, the slope of the line can be used to calculate Ea.

3. What units are used for Ea?

Ea is typically expressed in units of joules per mole (J/mol) or kilojoules per mole (kJ/mol). It can also be represented in units of kilocalories per mole (kcal/mol) or electron volts (eV).

4. Can Ea be negative?

No, Ea cannot be negative. It represents the minimum amount of energy required for a reaction to occur, so it must always be a positive value.

5. What factors can affect the accuracy of Ea calculations?

The accuracy of Ea calculations can be affected by the quality of the data used, potential errors in experimental measurements, and assumptions made in the calculation method. It is important to carefully consider and validate all data and methods used in order to obtain accurate results.

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