Kinetics, a study of reaction rates
Calculating reaction rates from change in concentration over time.
The reaction rate is equal to the amount of reaction during a specified time interval.
The amount of reaction can be calculated from the change in concentration of a product or reactant during that time interval by dividing that change by the coefficient of the substance in the balanced equation for the reaction.
Δ[A] is read change in concentration of A and equals the final - initial concentrations of A.
As reaction rates must always be positive, rate is calculated using the negative of a change in concentration of a reactant.
How is reaction rate related to the rate of appearance of products and disappearance of reactants?
What is the unit of rate?
The reaction rate is equal to the amount of reaction during a specified time interval.
The amount of reaction can be calculated from the change in concentration of a product or reactant during that time interval by dividing that change by the coefficient of the substance in the balanced equation for the reaction.
For aA + bB 
cC + dD
A, B, C and D are substances.
a, b, c and d are coefficients.
cC + dDA, B, C and D are substances.
a, b, c and d are coefficients.
| reaction rate = | –Δ[A] | = | –Δ[B] | = | Δ[C] | = | Δ[D] |
| a × Δt | b × Δt | c × Δt | d× Δt |
Δ[A] is read change in concentration of A and equals the final - initial concentrations of A.
As reaction rates must always be positive, rate is calculated using the negative of a change in concentration of a reactant.
How is reaction rate related to the rate of appearance of products and disappearance of reactants?
The relative rates of appearance and disappearance of various reactants and products depends on their coefficient in the balanced equation.
Thus the reaction rate is calculated by dividing the change in concentration of that substance by the coefficient associated with that substance in the balanced equation for the reaction.
Thus the reaction rate is calculated by dividing the change in concentration of that substance by the coefficient associated with that substance in the balanced equation for the reaction.
What is the unit of rate?
The unit associated with reaction rate is concentration per unit time.
If concentration is measured in and time in seconds, rate has the unit s–1.
If concentration is measured in and time in seconds, rate has the unit s–1.