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# Using the Arrhenius equation

How to use the Arrhenius equation to calculate the activation energy.

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• Is there a specific EQUATION to find A so we do not have to plot in case we don't have a graphing calc??
• k = A e^(-Ea/RT)
• For the first problem, How did you know it was a first order rxn?
• In this problem, the unit of the rate constants show that it is a 1st-order reaction. The only reactions that have the unit 1/s for k are 1st-order reactions.
• why the slope is -E/R why it is not -E/T or 1/T
• R is a constant while temperature is not.
• is y=mx+b the same as y=mx+c in the UK?
• Yes, I thought the same when I saw him write "b" as the intercept. In the UK, we always use "c" :-)
• For T1 and T2, would it be the same as saying Ti and Tf?

Ti meaning Initial Temperature
Tf meaning Final Temperature
• Yes, of corse it is same. You can write whatever you want ,but provide the correct value
• Shouldn't the Ea be negative? -19149=-Ea/8.314
-19149*8.314=-Ea
Did you multipy by -8.314
• The negatives cancel. Also, think about activation energy (Ea) being a hill that has to be climbed (positive) versus a ditch (negative)
• how do you find ln A without the calculator?
• You can't do it easily without a calculator.
If you don't have a personal calculator, you can use an on-line calculator like this:
http://www.eeweb.com/toolbox/calculator
or simply enter an expression like ln 2 in the search box of your search engine.
• what does inK=lnA-Ea/RT mean?
(1 vote)
• It is ARRHENIUS EQUATION used to find activating energy or complex of the reaction when rate constant and frequency factor and temperature are given . It can also be used to find any of the 4 date if other 3are provided