Kinetics Flashcards
Define activation energy
The minimum amount of energy needed to break bonds within the reactants to start the reaction
What does collision theory say?
A reaction won’t take place between two particles unless they collide with at least a certain minimum amount of kinetic energy and in the right direction
What does a Maxwell-Boltzmann distribution show?
Not all particles have the same amount of energy. Some have loads, some have little, others in-between
Describe the effect an increase in temperature would have on reaction rate
At higher temperatures particles have more kinetic energy so they move faster. This means more molecules have the required energy to react. As a result the particles collide with each other more frequently and with more energy increasing the chances of successful collisions occurring. At the rate of reaction increases.
Describe the effect an increase in concentration would have on reaction rate
And increased concentration means more particles in the same volume. The particles are therefore closer together. This results in particles colliding with each other more frequently. More frequent collisions means an increased chance of successful collisions occurring full stops are reaction rate increases.
Describe the effect an increase in surface area would have on the rate of reaction
The reactions of solids can only take place at the surface of the solid. If the solid is broken into smaller pieces you get more surface area for reactions to take place on and therefore a faster reaction.
Describe the effect an increase in pressure would have on the rate of reaction
Increased pressure pushes particles closer together. This results in particles colliding with each other more frequently. More frequent collisions means an increased chance of successful collisions occurring so reaction rate increases.
What is a catalyst?
A substance that increases the rate of reaction by providing an alternate reaction pathway with a lower activation energy. The catalyst is unchanged at the end of reaction. They only catalyse specific reactions.
Describe how you could measure the rate of a reaction where one of the products is a gas
Add the reactants to a conical flask.
Measure the conical flask on a mass balance and start a stopwatch
Read off the mass at regular time intervals and record these in a table with columns : mass and time
Describe another method that would allow you to measure the rate of reaction where one of the products is a gas
Add the reactants to a conical flask that is connected to a gas syringe and start a stopwatch.
Read off the volume of gas in the gas syringe at regular intervals. Record these in a table with columns: time and volume
Describe how you could measure the rate of reaction where one of the products is a precipitate
On a white tile draw a black cross-mark
Place a conical flask on the white tile
Add the reactants to the conical flask and start a stopwatch
Stop the timer when the black mark cannot be seen
