What is meant by reaction rate?

Consider the reaction:

2 H₂O₂ -----> 2 H₂O + O₂(g)

The rate is defined as the change in concentration of either a reactant or product with respect to time. The change in concentration of H₂O₂ with respect to time is the rate of reaction of the H₂O₂ in this reaction. The rate of production of water is the same as the rate of disappearance of peroxide. The rate of production of oxygen is half the rate of reaction of peroxide, however, because 2 moles of peroxide produce one mole of oxygen.

or

rate = -Δconc H₂O₂ / Δt = -Δ[H₂O₂] / Δt

where

ΔConc H₂O₂ = conc H₂O₂(at time2) - conc H₂O₂(at time1)
Δt = time2 - time1

Units of measure of rates are frequently moles/(liter x sec).

Rates are measured by measuring the concentration of either a reactant or a product as a function of time.

Reaction Rates