Kinetics And Equilibria Flashcards
(30 cards)
What is collision theory?
Collision theory states the rate of reaction is directly proportionate to the frequency of successful collisions per second
Define a successful collision?
The particles must collide with enough energy (activation energy) to break bonds in the correct orientation
What happens if they do bjt have enough activation energy?
They will just bounce of eachother
What factors increase rate of reaction?
+Temperature
+Pressure
+concentration
+Temperature
+Pressure
+concentration
How to determine ROR?
Measure mass of product formed or (if gas capture in upturned measuring cylinder or gas syringe) mass or reactant used up over time (balance)
What is transition state?
The point where when the particles collide in correct orientation with wnough activation energy and the bond breaks then reform that point it is unstable tho
Can be represented at the peak of the curve on an Enthalpy diagram
Define activation energy in a level terms?
The Enthalpy change from the reactant to the transition state
Define a catalyst and how it works?
A catalyst speeds up a chemical reaction without being used or changed in the process by providing an alternative pathway with a lower activation energy barrier
New activation energy is shown as Ec not Ea
What are pros and cons economically!
Pros: Less energy therefore money spent less need for fossil fuels
Cons: some catalyst can be toxic for the environment
What is a homogenous catalyst and how does it work?
Homogenous catalyst are catalyst that have the same physical state as the reactants
They work by 2 stages first stage they react with the reactants forming an intermediate that then reacts again to reform the catalyst
What is a heterogenous catalyst and how does it work
Heterogenous catalyst have a different physical state as the reactants (mostly a solid with gas but can be others)
Work by the reactants forming weak bonds to the catalyst (adsorption) then reacting to form product then detaching (desorption)
What does the maxwell boltzman distribution curve represent and describe it?
Graph represents all of the particles and there energies in a system
The area under graph represents all the particles in a system
The graph neber touched the x axis because there’s no max energy
The most probable energy is at the peak but the mean energy is slightly to the left because the very high energy particles move the mean to the right
Starts at origin (0,0) meaning no particles with 0 energy
What happens to the shape of the graph if we increase temperature?
The peak gets lower but moves more to the right meaning theres more particles with higher energy but the area under the graph remains the SAME
What is a reversible reaction?
A reversible reaction refers to a reaction where the products are unstable and can reform the reactants
Represented by double arrows which mean the reaction Can attain dynamic equilibrium
Main points about reversible reactions?
Equilibrium is the point where the forward and backward reaction occur at the same rate and the concentrations of the products and reactants remain constant
NOT the same The reactants can have a higher concentration or vise versa
And equilibrium can be approached from either side
Define le Chateliers’s principle?
When an external change is applied on a system at equilibrium the system will shift equilibrium in the direction which counteracts and reduces that change
What is meant by position of equilibrium?
The position of equilibrium can either lie to the left r right depending on which side has the higher concentration at equilibrium
Describe the effect of increasing concentration on the effect of equilibrium using le chateliers principle?
If we increase the concentration on one side le chateliers principle says that equilibrium will shift to the Side that reduces that change so if we increase the concentration of reactants then more reactants will react to form products therefore shifting the equilibrium to the right
Define a closed system?
A system where no atoms can leave or enter the system
Describe the effect of pressure on a system at equilibrium using le chateliers principle?
Pressure is directly proportionate to the no of moles more moles more pressure
If the external change is to reduce pressure le chateliers principle says that the system will counteract that change so equilibrium will shift in the direction that increases pressure which is whichever side that has more moles
What if bkth moth sides have the same amount of moles?
Then theres no shift in equilibrium
Describe the effect of temperature on a system at equilibrium using le chateliers principle?
One side of the reaction has to be exothermic and the other has to be endothermic
If we increase temperature the equilibrium will shift in the direction which will reduce temperature therefore equilibrium will shift to the direction that is endothermic and vise versa
What is the effect of a catalyst on reversible reaction?
A catalyst increases the rate of the forward and backward reaction at the same rate it has no effect on the position of equilibrium only makes the system attain equilibrium faster
