Chapter 10 Reaction rates and Equilibrium Flashcards
WHat is meant by rate of reaction
the rate of a chemical reaction measures how fast a reactant is being used up or how fast the product is made.
Which factors can change the rate of reaction
concentration
temperature
use of a catalyst
surface area of solid reactants
Why are some collisions effective and other ineffective
two conditions have to be met:
1. the particles collide with the correct orientation
2. the particles have sufficient energy to overcome the activation energy barrier of the reaction.
How does increasing the concentration affect the rate of reaction
when increasesd, the number of particles in the same volume is the same. The particles are then closer together and there are more of them so there will be more effective collisions and an increased rate of reaction
How does increasing the pressure of a gas affect the rate of reaction
when a gas is compressed into a smaller volume the pressure of a gas is increased and the rate of reaction increases. The concentration of the gas molecules increases as the same number of gas molecules occupy a smaller volume. The gas molecules are close togerher and collide more frequently, leading to more effective collisions in the same time.
Methods of following the progress of reaction
monitor the removal of a reactant or the formation of a product.
if it is a gas product then collect the gas in a syringe and calculate the volume.
What does a catalyst do
it is a substance that changes the rate of reaction without undergoing any permanent change itself.
the catalyst isn’t used up in a reaction
the catalyst may react witha a reactant to form an intermediate or may provide a surface on whcih the reaction can take place.
at the end of the reaction the catalyst is regenerated.
it decreases the activation energy
Homogenous catalyst
It has the same physical state as the reactant. And it reacts with the reactants to form an intermediate. The intermediate then breaks down to give the product and regenerates the catalyst.
Heterogenous catalyst
A heterogenous catalyst has a different physical state from the reactants. The catalyst comes into contact with the reactants, the reactants molecules are weakly bonded onto the surface of the catalyst, where the reaction takes place. After reaction, the product molecules leave the surface of the catalyst by desorption.
