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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: mycotheologist on March 25, 2012, 01:51:45 PM

Title: Using an Arrhenius plot
Post by: mycotheologist on March 25, 2012, 01:51:45 PM

Heres the question:
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Kinetics is probably my weakest area in chemistry so I'm struggling. To find the shelf life, I need to use the Arrhenius equation but I don't know the activation energy Ea or the A constant. So I converted 2 those percentages into rates and got:
At 40C, rate = 0.082 %/month
At 60C, rate = 0.39 %/month
I know that if I plot 1/T vs. lnk, I get an Arrhenius plot and then I can find Ea from the slope and A from the y-intercept but I don't have k. Can I just use the rates that I have instead of k?

Title: Re: Using an Arrhenius plot
Post by: blaisem on March 25, 2012, 06:32:29 PM

Yes.  My understanding is that it is assumed the reaction is first order.  Therefore, k and the rate you calculated are the same thing.  The units of A will reflect this in your equation.