Topic 6 - Rate And Extent Of Chemical Change Flashcards
What is the collision theory
In order for a chemical reaction to happen reactant particles must collide with each other and the particles must have enough energy for them to react
What’s a successful collision
A collision that produces a reaction
What is activation energy
The minimum amount of energy needed for a collision to be successful
What’s the equation for mean rate of reaction
Quantity of reactant used or product formed ÷ time taken
What are other ways to determine the rate of reaction
Measuring mass (when a gas is produced), measuring volume (useful when a gas is produced, using a gas syringe etc)
What happens when the concentration of a reacting solution or the pressure of a reacting gas is increased
- the reactant particles become more crowded
- the frequency of collisions between reactant particles increases
- the rate of reaction increases
What happens when the surface area to volume ratio of the reactant increases
- more reactant particles are exposed at the surface
- the frequency of collisions between reactant particles increases
- the rate of reaction increases
How do you increase the surface area to volume ratio
Break a large lump into smaller chunks or grind it into a powder
What would happen if the temperature of the reaction mixture is increased
- reactant particles move more quickly
- the energy of the particles increases
- the proportion of collisions which are successful increases
- the rate of reaction increases
What is a catalyst
A substance that increases the rate of reaction, does not alter the products of the reaction, and is not used up at then end of the reaction
How do catalysts work
They provide an alternative reaction pathway that has a lower activation energy
What happens if you add a catalyst to a reaction
- it increases the frequency of successful collisions as more particles have energy greater than the activation energy
- rate of reaction increases
What’s a reversible reaction
The products of the reaction can react together to produce the original reactants . The same amount of energy is transferred in both the forward and backward reaction but one direction will be endothermic and the other exothermic
What is dynamic equlibrium
The forwards and backwards reactions are still happening, they have the same rate of reaction, the concentrations of all the reacting substances remain constant. This haplend when a reversible reaction happens in a closed container.
What is Le Chatelier’s principle
The equilibrium can be changed by changing the reacting conditions through either changing the concentration, pressure, or temperature
