The Rate and Extent of Chemical Change Flashcards
What is the formulae to find the mean rate of reaction?
Mean rate of reaction =
↳ amount of product formed / time.
or
↳ amount of reactant used / time.
How do you find the rate on a rate graphs?
① find the rate at a specific point by drawing a tangent to the curve at that point.
② rate = gradient = change in y / change in x.
What are the factors that affect the rate of reactions?
> temperature. > pressure or concentration. > surface area. > collision theory. > catalysts.
What does the rate of chemical reaction depend on?
> collision frequency.
↳ the more collisions between particles, the faster the rate of reaction.
collision energy.
↳ enough energy needs to be transferred in a collision to overcome the activation energy and break the bonds to start the reaction.
What are catalysts?
Speed up reactions without being used up by providing an alternating pathway for the reaction.
What does the collision theory explain?
How various factors affect rates of reactions.
How does temperature affect the rate of reaction?
When the temperature is increased, the particles move faster causing more frequent collisions making enough energy to make the reaction happen.
How does the concentration affect the rate of reaction?
If solution more concentrated, it means there are more particles knocking about in the same volume of water or other solvent.
How does the surface area affect the rate of reaction?
If one of the reactants is a solid then breaking it up into smaller pieces will increase it surface area to volume ratio meaning the particles around will have more area to work on so there will be collisions more frequently.
How does a catalyst affect the rate of reaction?
Decreases the activation energy needed for the reaction to occur.
What does the collision theory say?
Chemical reactions can only occur when reacting particles collide with each other and with sufficient energy.
What happens if the temperature of a system at equilibrium is increased?
> the relative amount of products at equilibrium increases for an endothermic reaction.
the relative amount of products at equilibrium decreases for an exothermic reaction.
What happens if the temperature of a system at equilibrium is decreased?
> the relative amount of products at equilibrium decreases for an endothermic reaction.
the relative amount of products at equilibrium increases for an exothermic reaction.
How does the pressure affect the rate of reaction?
When pressure of gas is increased, it means that the same number of particles occupies a smaller space making collisions between reactant particles more frequent.
