Factors Affecting Reaction Rates

Speed of chemical reactions

Rate at which: reactants are used OR products are formed

Concentration

Surface Area

Pressure (gases only)

Temperature

Catalyst

When the reactants are concentrated, more chance of colliding and therefore making more products

Molarity

When there are many molecules of each reactant, the collisions happen often and the reaction is quick

When few atoms are left, the collisions happen less often

and the reaction slows down and eventually ends

Large block of reactantsMost atoms trapped inside, aren’t reacting

Smaller pieces, increase surface area, leaving more reactants exposed to react

As Pressure increases, volume decreases (boyle’s law)

Increasing pressure causes particles to collide more oftenTherefore increasing rate

of reaction

When two particles collide they require Activation Energy to react.Too Slow, so they bounced offLets speed it up a little

Finally these particles had enough combined energy to react!

Still not enough combined energy

Increases speed of particles, increases energy of particles to collide and number of collisions

Speeds up rate of reaction, without changing reaction

Lowers activation energy

Help rearrange bonds to form products

More particles are allowed to react

Concentration: concentration of reactants, faster rate of reaction

Surface Area: SA (smaller pieces), faster rate of reaction

Pressure (gases only): P, more collisions, faster rate of reaction

Temperature: T, faster particles & more collisions, faster rate of reaction

Catalyst: Presence of catalyst, faster rate of reaction, doesn’t change

reaction, lowers activation energy