Kinetics (3.1.5-Phys.) Flashcards
Define ‘Collision Theory’
1) Particles must collide
2) Collision must have E ≥ Eₐ
Define activation energy
The minimum energy required for a reaction to occur.
Define rate
[Mass of product formed (g)] / [time (s)]
What increases rate of reaction and how?
1) Surface Area: Increases because more particles exposed, higher successful collision frequency
2) Pressure/ Concentration:
Increases because more particle per cm³, higher successful collision frequency.
What is a catalyst?
A substance that can speed up the rate of a reaction but remains chemically unchanged itself
How does a catalyst work?
It provides an alternative route with a lower activation energy.
Describe a standard Maxwell-Boltzman curve
A curve with a peak on the left hand side to that it is NOT symmetrical.
The curve should not finish at the x-axis or level off, and it should begin at the origin.
What labels does a Maxwell-Boltzman diagram involve?
Y-axis: Number of particles X-axis: Energy Also on X-axis: Emp: E of most particles- under peak Eave: average E, near middle but closer to peak Ea- activation energy, near end of curve
What does the shaded area after Ea represent?
The number of particle with energy greater or equal to the activation energy.
How would you draw a Maxwell-Boltzman distribution for the effect of a higher temperature?
- Lower peak
- More to the right
- Higher area under the curve following Ea
What does the Maxwell-Boltzman distribution for higher temperature reveal about the effect of temperature on the rate?
This means that at the higher temperature, MANY more particles have energy greater than or equal to the activation energy, so there will be many more successful collisions.
How would you draw a Maxwell-Boltzman distribution for the effect of a catalyst?
- The same curve
- An additional label that says ‘Ecat’
