1.5 Kinetics Flashcards
State the collision theory
For a reaction to occur, particles must collide
What is the rate equation
Amount of products made / time
A successful collision is when particles collide and a reaction happens. State the conditions necessary
- particles must have energy equal to or greater than activation energy
- particles must have correct orientation (must move in the correct direction)
What is activation energy
Minimum energy required for a reaction to occur
For an exothermic reaction label the activation energy, what does the maximum energy represent
- At this point bonds have sufficient energy to break
Label activation energy for endothermic reaction
What is a catalyst
Catalyst increases rate of reaction by providing an alternative pathway with a lower activation energy
What does the area under Maxwell-Boltzmann curve represent
Total number of molecules
Label on a Maxwell-Boltzmann distribution graph, where the most likely energy is represented and where the mean energy of particles is
Show and state what happens to Maxwell-Boltzmann distribution curve, when temperature of a reaction mixture is increased
State how increase in temperature affects rate of reaction
- particles are moving faster as they have higher energy
-More frequent collisions - more molecules have energy higher than Activation energy
- hence there are more successful collisions
How does increasing pressure and concentration affect rate of reaction
Increasing any of these factors increases rates of reaction
Particles are closer together and collide more frequently
There are more frequent and successful collision and higher chance of a reaction
Where to do place solution in experiment if gas is harmful or toxic
Fume cupboard
How to time how long it takes a precipitate to disappear
State problem with this
Place a cross on paper and time how long it takes to cross to disappear (precipitate to form)
Problem - this is difficult to know when exactly the cross disappears. Try to use same observer to reduce errors
How to measure volume of gas produced
Measure amount of gas produced using a gas syringe. Measure over specified time
How does adding a catalyst affect Maxwell - Boltzmann distribution curve
Curve unchanged, activation energy shifts to the left
Only do part D)
Mark scheme says peak energy should be same at X
However, both lines should not touch as red line should have a lower area
A
What should you consider if asked for a line of best fit
Curve can also be drawn and it does not have to start at 0,0
Student is timing something, suggest why they measure to the nearest second and not to the nearest 0.01 second
It is harder to judge to the nearest 0.01 second
Suggest by considering products of reaction, why a small amount of reactants are used in the experiment
SO2 is toxic, so to limit the amount of SO2 formed
Explain why student decided not to carry out experiments at lower temperatures
Reaction would be too slow
B
D
Explain in general terms how a catalyst increases rate of reaction
Provides a different pathway with lower activation energy
Explain in terms of collision theory the effect of increasing concentration of reactants on rate of reaction
More particles in given volume and more particles closer together
More successful frequency collisions between particles
Explain effect of lowering temperature on rate of reaction
Less molecules with energy equal to or greater than the activation energy
Fewer successful collisions in a given time
Number of molecules has been reduced
Particles are spread further apart
Free successful collisions in a given time
A
A
