Question 1

What is a rate constant?

Accepted Answer

The rate constant (k) is a proportionality constant in the rate law that relates reaction rate to reactant concentrations. Its value depends on temperature and the specific reaction, but not on concentrations.

Question 2

How does temperature affect the rate constant?

Accepted Answer

The rate constant increases with temperature, typically doubling for every 10°C rise. The Arrhenius equation describes this: k = A·exp(-Ea/RT). See the activation energy calculator for details.

Question 3

What determines reaction order?

Accepted Answer

Reaction order is determined experimentally by measuring how the rate changes when concentrations are varied. It is NOT determined from the balanced equation coefficients (except for elementary reactions).

Question 4

What are the units of k?

Accepted Answer

Units of k depend on overall order: zero order = mol/(L·s), first order = s⁻¹, second order = L/(mol·s). The units ensure the rate always comes out in mol/(L·s).

Reaction Rate Constant Calculator

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