Reaction Rates 3.10.1 Flashcards
rate of chemical reaction?
Measures how fast a reactant is being used up or how how fast a product is being formed.
Equation for rate of reaction
Rate = change in concentration/time
Which factors affect the rate of chemical reaction?
- Concentration of solution
- Surface area of solid reactants
- Temperature
- Pressure of gas
What must happen for a reaction to occur
For a reaction to occur particles must collide.
Collision Theory: What must particles have for a reaction to occur?
Particles must have sufficient energy to overcome the activation energy barrier of the reaction and correct orientation.
Activation energy
The minimum amount of energy required that a particle needs for a reaction to occur.
How does increasing the concentration affect the rate of reaction?
The rate of reaction increases because the number of particles have increased and are close together and therefore collide more frequently. Therefore there will be more successful collisions.
How does increasing the pressure of gas affect the rate of reaction?
The rate of reaction increases. The gas molecules occupy a smaller volume. The gas molecules are closer together and collide more frequently, leading to a high frequency of successful collisions.
What are two methods that can used to determine the rate of reaction that produces gas?
- Monitoring the volume of gas produced at regular time intervals using gas collection.
- Monitoring the loss of mass of reactants using a balance.
Catalyst
A substance that increases the rate of reaction without being used up (chemically unchanged) , by providing an alternative pathway by lowering the activation energy– so a higher proportion of molecules have energy higher than EA.
Why do catalyst have sustainable and economic importance?
Products made faster and reactions can occur at lower temperatures. This saves energy and money. Less waste is produced and reduces CO2.
Catalyst may react with reactant to form an…
Intermediate. The catalyst is reformed again. (Homogenous)
Heterogenous catalyst
- A catalyst in a different phase/state from the reactants.
- Reactant molecules are absorbed onto the surface of the catalyst where the reaction takes place.
- After reaction, the product molecules leave the surface of the catalyst by desorption.
Which industrial processes use heterogenous catalyst?
The Haber process where a solid iron catalyst is used to make ammonia or hydrogenation of alkenes where solid Nickel is used.
Homogenous Catalyst
A catalyst that is in same phase as the reactants.
Catalyst reacts with reactants to form an intermediate.
The intermediate then breaks down to give the product and regenerates the catalyst.
