Chemical Forums

Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: docpar on March 22, 2009, 07:51:48 PM

Title: Frequency Factor and Activation Energy?
Post by: docpar on March 22, 2009, 07:51:48 PM
Hi, I have a homework problem that I am having some problems understanding.

It goes like the following:

The decomposition of N2O5(ga) has the following rate constants at the four temperatures below:

T(k)     K
658    2.14x10^5
673    3.23x10^5
688    4.81x10^5
703    7.03x10^5

A)determine the activation energy as well as the frequency factor.
B)calculate the rate constant for 300k

For A, i got Ea=98853.46 J/mol and A=1.54x10^13
I used lnK= (-Ea/R)(1/T) + lnA
This equation is like the equation for a line, so i graphed all the values given above, and figured that the slope would be the activation energy (i did this because the problem required that I use all the data given).
To find A (frequency factor), i simply used a value from the data given in the equation K=Ae^-Ea/RT

B i got K=1.29x10^ -90
I used the formula K1/K2=e^(-Ea/R (1/T1)-(1/T2))

These all seem very wrong, are they? I dont know if i did them properly

Thanks for any *delete me*