Reaction Rates

What is collision theory’s

chemical reactions occur when particles of reactants successfully collide to produce new chemical substances

what must a successful particle collision have

must have enough energy and correct orientation to result in the formation of products

what is rate of reaction

is the decrease in concentration of reactants or the increase in concentration of products with time

how is the rate of chemical reaction determined

by the rate of collisions and by the fraction of the collisions that is effective in producing new species

as a reaction proceeds, what will happen to the amount of reacts present and amount of products present

the amount of reactants present will decrease while the amount of products will increase (known as reaction rate)

how are reaction rates influenced

pressure

concentration of the reactants

temperature

surface area

catalyst

how does pressure influence reaction rates

it affects gas reaction systems the most.

• when pressure is applied to the gases of a reaction systems, molecules are pushed together causing the volume of gas to decrease resulting in an increase of the concentration of reacting gases

• the increase in gas concentration increases the chance of reacting molecules colliding effectively to form products

• when pressure decreases, the opposite occurs

how does concentration of the reactants influence reaction rates

as concentration of the reactants increase the rate of reaction generally increases because more substance molecules are present

• this increases the chance of reacting molecules colliding effectively to form products

• when concentration of a reactant decreases, the opposite occurs

how does temperature influence reaction rates

increasing temperature of a reaction causes the movement of molecules (KE) to increase

• increased movement increases chance of reacting molecules colliding effectively to form products

• when temperature decreases, opposite occurs

how does surface area influence reaction rates

increasing surface area, increases the rate of reaction because more reacting surface molecules are exposed

• this greater exposure increases the chance of reactant molecules, colliding effectively to form products

how does a catalyst influence reaction rates

A substance that increases the rate of a chemical reaction by lowering the activation energy of the reaction

• activation, energy energy required to initiate a chemical

• Catalyst create an alternative reaction pathway, allowing the reaction to occur fast faster. Think of the catalyst as creating a shortcut from reactants to product

• catalyst make the particles involved in collisions have a better orientation, resulting in more successful collisions and an increase reaction rate

• an inhibitor is a substance that decreases the rate of a chemical