6. The Rate And Extent Of Chemical Change Flashcards
(14 cards)
What are the two ways to calculate the rate of reaction?
Mass of reactant used / time AND Volume of product formed / time
What is needed for a successful reaction? [3 marks]
- Particles must collide
- Particles must collide in the correct orientation
- Particles must have enough energy to react
Why does the rate of reaction increase with more particles?
More particles for more frequent collisions
Why does the rate of reaction increase when the temperature is increased?
Particles have more kinetic energy for successful collisions - Increases the frequency of collisions
What does a catalyst do?
A catalyst provides an alternate reaction pathway with a lower activation energy. It increases the rate of reaction. They are usually transition metals and are not used up in a reaction.
What has a higher SA:V ratio and why? - Larger marble chips or smaller marble chips
Smaller marble chips have a higher surface area:volume ratio.
What does a higher SA:V ratio mean
With a higher SA:V ratio,
- There are more places for a reaction to occur
- There are more frequent collisions
- There is a higher rate of reaction
Define a reversible reaction
A reversible reaction is one in which the products of a reaction can react with each other to reform the original reactants.
When does an equilibrium occur?
An equilibrium occurs when the rate of the forward reaction is equal to the rate of the backwards reaction within a closed system
When a reaction is at equilibrium, what will you be able to observe?
It will look like no reaction is happening
What happens at the start of a reaction (in terms of speed and amount of reactants and products)?
At the start of the reaction, there is lots of the reactants, and no products. The forwards reaction is happening very fast and the backwards reaction would not have started yet.
What happens as the reactants turn into products?
The forwards reaction will slow down, and the backwards reaction will speed up.
Eventually, the rate of each reaction will even out, both reactions are happening at the same speed so they are at equilibrium.
What happens to the position of equilibrium when there are more products than reactants, or the other way around?
- When there are more products than reactants, the equilibrium lies to the right
- When there are more reactants and less products, the equilibrium lies to the left
What is Le Chatelier’s Principle?
Says that when a change is imposed on a system at equilibrium, the equilibrium will shift to counteract the change.
