Reaction Rates

Reaction RatesSpeed matters!*Watch a Video!*Reaction RateDecrease in concentration of reactants with time orIncrease in concentration of products with time [reactant or product] M mol/L time s s

==Reaction Rate Example :

[Products] Increase[Reactants] DecreaseH2 + I2 2 HIReaction Rate Example[HI] at time t2 [HI] at time t1 [HI] t2 t1 t0.09 M 0.08 M 0.01 M 7 s 5 s 2s

=== 0.005 M/s Factors affecting Reaction RatesTemperatureConcentrationPressureSurface AreaCatalyst

Temperature Increasing temperature generally increases reaction rates.Increasing temperature increases the average kinetic energy of particles reactant particles collide more frequentlyIncreasing temperature by 10 K can double a reaction rate.

Concentration & PressureAs concentration increases, reaction rate increases.Increasing concentration increases the collision frequency.For Gas reactants, increasing Pressure increases the concentration of a gas, thus increasing the reaction rate.

Surface AreaIncreasing the surface area of solid reactants increases the opportunity for collisions, speeding up the reaction.Crushing solids increases the surface area, speeding up the reaction.

Catalysts speed up a reaction, not being used!

Catalyst & Activation Energy