Rate Constant Calculator
Calculate rate constants, reaction rates, and half-life for chemical kinetics
Calculate Rate Constant
Molecule A
Known Values
Rate Law
Total order of reaction: 1
Kinetics Results
Rate Law: rate = k[A]1
Order: 1 (Overall order of reaction)
Quick Examples
Zero Order
2NH₃(g) → N₂(g) + 3H₂(g)
rate = k (independent of [NH₃])
t½ = [A]₀/(2k)
First Order
C₂H₆ → 2CH₃
rate = k[C₂H₆]
t½ = 0.693/k
Second Order
H₂ + I₂ → 2HI
rate = k[H₂][I₂]
t½ = 1/(k[A]₀)
Understanding Rate Constants and Chemical Kinetics
What is a Rate Constant?
The rate constant (k) is a proportionality constant that relates the reaction rate to the concentrations of reactants. It's specific to each reaction at a given temperature and provides insight into how fast a reaction proceeds.
Rate Law
rate = k[A]m[B]n
where m and n are the orders of reaction
Reaction Orders
Zero Order (n=0)
Rate independent of concentration
Units: M/time
First Order (n=1)
Rate proportional to concentration
Units: 1/time
Second Order (n=2)
Rate proportional to concentration²
Units: 1/(M⋅time)
Half-life Relationships
Zero Order
t½ = [A]₀ / (2k)
Half-life depends on initial concentration
First Order
t½ = 0.693 / k
Half-life is constant (independent of concentration)
Second Order
t½ = 1 / (k[A]₀)
Half-life inversely proportional to initial concentration