Kinetics Flashcards
What is the “activation energy?”
- Activation energy is the minimum amount of energy required for a reaction to occur/ for a succesful collision.
What is the idea of collision theory?
- In order for a reaction to occur, particles must collide with sufficient energy.
Explain why most collisions do not lead to a
reaction.
- Because a lot of the particles don’t have sufficient kinetic energy (ie. don’t have activation energy.)
- It’s rare for the particles to collide in the right direction.
How do you calculate the rate of reaction?
Amount of product used or reactant made/ time
Def of rate of reaction
- Change of concentration/ of product or reactant per unit time.
What main factors affect the rate of reaction?
1.) Temperature
2.) Concentration
3.) Pressure
4.) Presence of a catalyst.
Why does increase in temperature increase the rate of reaction?
- Increased frequency of succesful collisions between particles per unit time as particles have more kinetic energy.
- More energetic collisions as particles have more kinetic energy.
How does increase in pressure of gases affect the rate of reaction?
- Increased pressure increases rate of reaction.
- Molecules are closer together so increased frequency of succesful collisions per unit time- increasing rate of reaction.
How does increasing concentration affect the rate of reaction?
- Increased conc = increased reaction.
- More particles per unit volume so increased frequency of succesful collisions per unit time - increasing the rate of reaction.
What is a catlayst?
- A catalyst is a substance that increases the rate of a chemical reaction without being changed in chemical composition or amount (ie. the catalyst isn’t used up/ is unchanged at end of reaction)
() - extra info for clarification.
SPEC DEFINITION
How do catalysts actually increase the rate of reactions?
- Provide an alternative route for reaction to take place, with a lower activation energy.
Why are catalysts very useful in industrial reactions?
- Will increase the rate of reactions.
- Will mean reactions can occur at lower temperatures, saving energy and money.
What does energy profile look like w/ catalyst vs without?
- Without catalyst: activation energy is a lot larger (peaks higher.)
- W/ catalyst: activation energy is a lot smaller (peaks lower down.)
3 different ways rate of reaction can be measured from experiments.
- How long it takes precipitate to form.
- Amount of mass lost
- Volume of gas produced
How would you determine rate of reaction from volume of gas produced?
- Attach gas syringe to a conical flask with a bung (with reaction within the flask) and measure volume of gas collected in gas syringe over specified time.
