1. Excel workshop: Rate law and Activation energy determination
Giovanni Cruz

2. Reaction Rate Disappearance of reactant or appearance of product
Dependence of amount of initial reactant
A + B  AB
rate α [A]p or rate α [B]q or rate α [A]p [B]q or rate α [AB]r
rate =k [A]p [B]q
p and q are orders for A and B

3. Reaction Rate

4. Specific rate constant (k)
rate =k [A]p [B]q
Determined experimentally
Varies with temperature and catalyst
Independent of reactant concentration

5. Parameters [A] will differ in each reaction
Experiment perform at two temperature
rate= k [A]p[B]q
keeping [B] constant
rate= k’ [A]p
rate= -Δ[B]/Δt or rate= appearance of [AB]/Δt

6. Determination of Reaction Order, p, and Rate constants, k’
rate =k’ [A]p
log(rate) = log k’ + p log [A]
y= b + m x
y-intercept = log k’

7. Activation Energy (Ea)
Minimal energy to star a reaction.
Arrhenius equation
k=Ae-Ea/RT
R: Gas constant (8.314 J/mol K)
A: collision parameter
k: Specific rate canstant

8. Determination of Ea k=Ae-Ea/RT k1/k2 = (Ae-Ea/RT1) /(Ae-Ea/RT2)
ln (k1/k2)= - Ea/R (1/T1 – 1/T2)
Ea= - [R ln (k1/k2) ]/ (1/T1 – 1/T2)

9. Experiment Data from the experiment Temperature C° Reaction time (s)
Volumes of reactants (mL)

10. Data Analysis and calculation

11. Sorting data

12. Molarity calculation
M1V1=M2V2
M1V1=M2 V2

13. log [A] cal.
rate and log [rate] cal.
rate= [B]/s

14. Set table and add trendline

15. Arrange and label axis

17. Determination of Ea

18. Ea= - [R ln (k1/k2)] / (1/T1 – 1/T2)

19. Calculation of 1/t1-1/t2

20. Calculation of ln[k1/k2]

21. Verifying calculations
Ea= - [R ln (k1/k2)] / (1/T1 – 1/T2)

22. Results