Chemical Kinetics — Visual Guide — Summary | NoteTube

Concept Map

Energy Profile Diagram

Energy
  |
  |         ‾‾‾‾‾TS (transition state)
  |        /      \      ← Ea(forward) from reactants
  |       /        \     ← Ea(backward) from products
  |      /  catalyst\
  |     /  TS lower  \
  | [R]/              \[P]
  |
  +————————————————————→ Reaction coordinate

  $\Delta H$ = Ea(forward) − Ea(backward)
  Catalyst shifts TS downward; [R] and [P] levels unchanged

Linear Graph Identification

If this plot is linear...	Order is...	Slope gives...
$[A]$ vs $t$	Zero	$-k$
$\ln[A]$ vs $t$	First	$-k$
$1/[A]$ vs $t$	Second	$+k$
$\ln k$ vs $1/T$	—	$-E_a/R$

Half-Life Concentration Dependence

Order	$t_{1/2}$ formula	Dependence on $[A]_0$
0	$[A]_0 / (2k)$	Directly proportional
1	$0.693 / k$	None (independent)
2	$1 / (k[A]_0)$	Inversely proportional

Apparatus: Iodine Clock Reaction (concentration effect visualisation)

The iodine clock reaction visually demonstrates how concentration affects reaction rate: a sudden colour change occurs when the thiosulfate is consumed, timing the rate directly.

Arrhenius Plot

$\text{slope of } \ln k \text{ vs } \frac{1}{T} = -\frac{E_a}{R}$

ln k
 |  \
 |   \   slope = -Ea/R
 |    \
 |     \
 +------→  1/T

Higher $E_a$ → steeper (more negative) slope → $k$ more sensitive to temperature change.