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UnicornPanda UnicornPanda
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11 years ago
I can't seem to wrap my head around this equation. I'm working on my post-lab right now and I am going through my data. My excel sheet is attached.

But I have no idea how to solve for k, much less ln(k). Help?! =/
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wrote...
Staff Member
11 years ago
Use the values you found for k and click [ln] in your calculator, followed by the number, k. Or, better yet:

http://www.rapidtables.com/calc/math/Ln_Calc.htm
- Master of Science in Biology
- Bachelor of Science
UnicornPanda Author
wrote...
11 years ago
Yes, but I don't know how to solve for k at all. How do I find the activation energy or the frequency factor with the data that I have?
wrote...
Staff Member
11 years ago
Yes, but I don't know how to solve for k at all. How do I find the activation energy or the frequency factor with the data that I have?

Was a formula provided?
- Master of Science in Biology
- Bachelor of Science
UnicornPanda Author
wrote...
11 years ago
Yes, but I don't know how to solve for k at all. How do I find the activation energy or the frequency factor with the data that I have?

Was a formula provided?

This is what I have:

You will design this experiment to answer the following questions regarding this reaction:
C_4H_9Cl + NaOH Rightwards Arrow C_4H_9OH + NaCl

The Arrhenius equation is as follows:

k=Ae^(-E_a/RT)

Where R is 8.3145 Joules/mol-K
wrote...
Staff Member
11 years ago
Do we know little k, A, or -E_a ? We need to fill in 4 of the 5 variables in order to solve.
- Master of Science in Biology
- Bachelor of Science
UnicornPanda Author
wrote...
11 years ago
Quote
Do we know little k, A, or -E_a ? We need to fill in 4 of the 5 variables in order to solve.

K= Chemical Reaction Rate
A= Pre-Exponential Factor
Ea= Activation Energy
R= Gas Constant
T= Temperature in Kelvin
wrote...
Staff Member
11 years ago
I meant a quantitative value for them.
- Master of Science in Biology
- Bachelor of Science
wrote...
Staff Member
11 years ago
Both the Arrhenius activation energy and the rate constant k are usually experimentally determined.
- Master of Science in Biology
- Bachelor of Science
UnicornPanda Author
wrote...
11 years ago
Both the Arrhenius activation energy and the rate constant k are usually experimentally determined.

That's what I'm not sure of. In my post-lab it asks me to plot the Arrhenius equation and what was the activation energy determined from the experiment.

This is the data gathered from my experiment. It was water, acetone & 200 proof ethanol. with NaOH, blue indicator & t-butyl chloride

#1-5 Ratio (1:1) 1.5mL water & 1.5mL Acetone
1. @44.5 C - 30 seconds for reaction to occur
2. @35 C - 1 minute
3. 26.5 C - 2:15
4. 54.3 C - 22 s
5. 64.0 C - 10 s
6. Water & Ethanol (1:1) 1.5mL each @ 26.5 C - 1:15
7. Water, Ethanol & Acetone (1:1:1) 1mL each @ 26.5 C - 1:55
8. Water & Ethanol (1:2) 1.5mL each @ 26.5 C - 1:05
wrote...
Staff Member
11 years ago
Have you plotted ln k (y) versus 1/T ? The activation energy of a reaction is determined from the slope of the Arrhenius plot.

- Master of Science in Biology
- Bachelor of Science
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