the rate and extent of chemical change Flashcards
How do you calculate the mean rate of reaction?
mean rate of reaction = product formed OR reactant used / time
How do you calculate the mean rate of reaction on a graph of product formed or reactant used by time?
the gradient
What is collision theory?
Collision theory states that chemical reactions can only occur when reacting particles collide with sufficient energy. The rate is determined by the frequency of successful collisions.
What is activation energy?
Activation energy is the minimum energy required for the reactants to collide with sufficient energy.
What is the relationship between the rate of reaction and concentration?
As the concentration increases, the rate does as there are more particles to collide, so there is also more products.
What is the relationship between the rate of reaction and pressure of a gas?
As the pressure of a gas increases, the rate does as there are more particles in one place to collide.
What is the relationship between the rate of reaction and surface area of solids?
As the surface area of a solid increases, the rate does as more particles collide at once.
What is the relationship between the rate of reaction and the temperature?
As the temperature increases, the rate does as the frequency of collisions and the amount of force they hit each other with increases.
What are catalysts?
Catalysts increase the rate of chemical reactions but are not used up during the reaction. They allow reactions to be carried out quickly without having to raise the temperature as high, which saves money. They provide a different pathway with a lower activation energy.
What are reversible reactions?
Reversible reactions are when the products can react to produce the reactants.
How can the direction of a reversible reaction be changed? Give two examples.
The direction of a reversible reaction can be changed with conditions. For example, ammonium chloride (rr arrow) ammonia + hydrogen chloride - requires heat going forward, and cold backward
- if exothermic one way, then endothermic the other by the same amount of energy
hydrated copper sulfate (rr arrow) anhydrous copper sulfate + water - endo forward, exo backwards
- hydrated copper sulfate is blue, anhydrous copper sulfate is white
What is equilibrium?
Equilibrium is when a reversible reaction is in a closed system and the forward and reverse reactions occur at exactly the same rate.
What us Le Chatelier’s Principle?
Le Chatelier’s Principle:
if a change is made to conditions in equilibrium, then the system responds to counteract that change
What will happen if at equilibrium, the concentration of the reactant increases?
If at equilibrium, the concentration of the reactant increases, more products will be formed until equilibrium is reached again.
What will happen if at equilibrium, the temperature increases in this reaction?
2NO2 (rr arrow) N204, exo forward endo backward
2NO2 (rr arrow) N204, exo forward endo backward
If at equilibrium, the temperature increases, the equilibrium produces more reactant (shifts to the left) to decrease the temperature.
