The rate constant for the reaction: NO2(g)+O2(g)---->NO3(g)+O2(g) was determined over a range of 40.0 K, with the following results. Determine the activation energy for the reaction (kJ/mol) and calculate the rate constant of the reaction at 300K?
T (K) k (M-1s-1)
203 4.14 x 105
213 7.30 x 105
223 1.22 x 106
233 1.96 x 106
243 3.02 x 106
T (K) k (M-1s-1)
203 4.14 x 105
213 7.30 x 105
223 1.22 x 106
233 1.96 x 106
243 3.02 x 106
1 Answer
#E_a = "20.37 kJ/mol"#
#k = 2.051 xx 10^7 "M"^(-1)"s"^(-1)#
Does it make physical sense that
You should plot the data in Excel. Reactions following Arrhenius kinetics obey the Arrhenius equation.
#k = Ae^(-E_a//RT)#
Show that
#ln k = ln A - E_a/(RT)#
so that:
#barul|stackrel(" ")(" "ln k = -E_a/R 1/T + ln A" ")|#
Then notice how
Add the slope and y-intercept.
And obtain them. Did you finish the graph?
So then... since the slope is
#-E_a/R = -"2450.6 K"# ,
#color(blue)(E_a) = -Rcdot"slope" = -"8.314 J/mol"cdot"K" cdot -"2450.6 K"#
#=# #"20374.3 J/mol"#
#= ulcolor(blue)"20.37 kJ/mol"#
The y-intercept is given as
#A = e^(25.005) = ul(7.237 xx 10^(10) "M"^(-1)"s"^(-1))#
And therefore, the rate constant at
#color(blue)(k) = Ae^(-E_a//RT)#
#= e^(25.005) "M"^(-1)"s"^(-1) cdot e^(-"2450.6 K"//"300 K")#
#= color(blue)ul(2.051 xx 10^7 "M"^(-1)"s"^(-1))#