Rate of Reaction
rate=−a1dtd[A]=−b1dtd[B]=+c1dtd[C]=+d1dtd[D]
Rate Law
rate=k[A]m[B]noverall order=m+n
Units of Rate Constant
[k]=(Lmol)1−n⋅s−1
| Order n | Units of k |
|---|
| 0 | molL−1s−1 |
| 1 | s−1 |
| 2 | Lmol−1s−1 |
| n | (molL−1)1−ns−1 |
Integrated Rate Laws
| Order | Integrated Law | Linear Plot |
|---|
| 0 | [A]=[A]0−kt | [A] vs t; slope =−k |
| 1 | ln[A]=ln[A]0−kt | ln[A] vs t; slope =−k |
| 2 | [A]1=[A]01+kt | 1/[A] vs t; slope =+k |
Half-Life Formulas
t1/2(0)=2k[A]0,t1/2(1)=k0.693=kln2,t1/2(2)=k[A]01
Arrhenius Equation
k=Ae−Ea/RT
lnk=lnA−RTEa,logk=logA−2.303RTEa
Slope of lnk vs 1/T: slope=−REa
Two-temperature form:
logk1k2=2.303REa(T11−T21),T1<T2
Activation Energy Relationship
Ea(forward)−Ea(backward)=ΔH
First-Order Half-Life Chain
[A]t=[A]0(21)nafter n half-lives
| n | [A]/[A]0 | % Completion |
|---|
| 1 | 0.500 | 50.0% |
| 2 | 0.250 | 75.0% |
| 3 | 0.125 | 87.5% |
| 4 | 0.0625 | 93.75% |
| 10 | 0.000977 | 99.9% |
Physical Constants
R=8.314Jmol−1K−1=1.987calmol−1K−1
ln2=0.693,log2=0.301,log4=0.602