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Activation Energy 
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#1
Feb2207, 04:04 PM

P: 34

1. The problem statement, all variables and given/known data
In Houston (near sea level), water boils at 100.0°C. In Cripple Creek, Colorado (near 9500 ft), it boils at 90.0°C. If it takes 5.6 min to cook an egg in Cripple Creek and 4.5 min in Houston, what is Ea for this process? What I do not understand is how I can figure this when the given formula for find Ea involves 2 unknown rate constants, and the formula for finding the rate constant given involves concentrations? So, how can I find the activation energy when given only 2 temperatures and 2 times? 2. Relevant equations ln(k2/k1)=(Ea/R)[(1/T2)(1/T1)]^1 k=rate1/(concetrations) 3. The attempt at a solution Not sure where to start... 


#2
Feb2207, 04:20 PM

P: 147

well, you have an equation for Ea... rearrange it to solve for Ea.
What variables do you know? What variables do you need? hint: you might not have to solve for each k value individually 


#3
Feb2207, 04:37 PM

P: 34

Ea=? T2=363.0K T1=372.0K time1=336s time2=270s R=8.314 J/mol*k Do I plug in the times for k? I am attempting it now, it looks as if it should still all cancel and leave me with J/mol which I want.... 


#4
Feb2207, 04:43 PM

P: 34

Activation Energy
Ok, I came up with 27279.97791 J/mol corrected to 27000 J/mol for sig figs, but Webassign says I am wrong, and within 10% of the correct answer. "Your answer is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out all intermediate results to at least fourdigit accuracy to minimize roundoff error."
Edit: I wrote a temp incorrectly in my conversion. Correct now! 


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