Hey everyone,

 

OK i am a bit stuck. I am doing some excercises on graphs and here is this table that contains data to plot a graph to determine the activation energy

 

T/K---------------------------- [math] 10^{13} k / cm^3 molecule^{-1} s^{-1} [/math]

 

300----------------------------1.04

350----------------------------1.87

400----------------------------3.04

450----------------------------4.60

500----------------------------6.58

 

I have constructed an arrhenius plot( ln(k) vs 1/T) from this data using excel. I am getting a slope of -1379.

 

using ln(k) =ln(A)-Ea/R *(1/T) so slope = -Ea/R and Ea = -slope*R this means that Ea is [math] (1379*8.3144)/10^{13} = 1.14 X 10^{-9} molecule^{-1} cm^3 s^{-1} K^{-1} [/math]. I want to get it into kJ mol-1. So I multiply it by Na and I get [math] 6.90 X 10^{14} mol^{-1} cm^3 s^{-1} K^{-1} [/math] how do I get rid of the other terms to get joules? Do I need to multiply the whole number by 10-6 and then take the square to make it [math] mol^{-1} m^{3} s^{-2} K^{-1} [/math] but I still would need to get rid of K? How do I do that?

 

sorry i know this is a bit messy but could anyone help. It will be most apprecitated. If any of you did the plot what value in kJ mol-1 are you getting? Thanks for your help

the units of R can also be written J/mol/K