✨Module 3 + 5: Rate of reaction Flashcards
In order to react, two particles must …
Collide with a certain amount of KE. They need to collide with correct orientation and have sufficient energy to overcome activation energy.
How does increasing concentration affect rate of reaction?
Increases - more particles in a given volume so more frequent collisions, successful.
If concentration doubles …
There are DOUBLE the number of particles per unit volume and DOUBLE the frequency of successful collisions.
How does increasing pressure affect rate of reaction?
Increases - more gas particles in a given volume, pushed closer together, more frequent successful collisions.
Surface area of …
Reactants also affect rate of reaction.
2 ways of monitoring the rate of reaction?
- Removal of reactant.
- Formation of product.
2 ways of monitoring rate of reaction for gases?
- Volume of gas produced at regular intervals using a gas syringe, measuring cylinder.
- Loss of mass of reactants using a balance.
Experiment to monitor gas rate of reaction?
Reactant solution is added to conical flask and a bung is replaced. Initial volume in measuring cylinder is recorded. Immediately start stopwatch and take the volume of gas produced at regular intervals until reaction is complete/no more gas is produced.
Define activation energy.
Minimum amount of KE needed to react and break the bonds to start the reaction/for particles to react.
Define a catalyst.
Increases rate of reaction by providing an alternative pathway with a lower activation energy for bonds to be broken and remade. So more molecules have energy above activation energy. Catalysts are chemically unchanged at the end of a reaction.
Iron catalyst is used to …
Make ammonia in the Haber process.
What is a heterogenous catalyst?
Has a different physical state to the reactants. They are usually solids with gaseous or aqueous solutions.
Where does the reaction happen on a heterogenous catalyst?
Reactant molecules are adsorbed (weakly bonded) to the SURFACE of catalyst, where the reaction takes place. Products leave surface of catalyst by desorption. Increasing SA increase no. molecules reacting at the same time.
Examples of heterogenous catalysts?
Fe (s) in the Haber process to make ammonia.
How does a catalytic converter work?
Has a large surface area for heterogenous catalysis to convert harmful exhaust fumes into less harmful gases that can be released into the atmosphere. CO and NO2 into CO2 and N2 gas.
