Equilibrium Flashcards
What are the features of a dynamic equilibrium?
the rate of the forward reaction is the same as the rate of the reverse reaction
the system must be closed
the conc of each substance involved remain constant
What is a closed system?
it is not possible for reactants or products to enter or leave the system
What is the enthalpy change equation?
change in enthalpy = Ea (forwards) - Ea (backwards)
forwards - reactants
backwards - products
What is Le chatelier’s principle?
when one of the conditions affecting the position of a dynamic equilibrium is altered, the position of equilibrium will shift in the direction that opposes the change
What happens to the equilibrium when you increase the temp of a reaction?
shifts to the endothermic direction because the system tries to decrease the temp
What happens to the equilibrium when you decrease the temp of a reaction?
equilibrium shifts to the exothermic direction as the system tries to raise the temp
What does shift mean in terms of equilibrium?
settling into a new equilibrium
What happens to the equilibrium when you increase the conc of the reactants?
the system tries to reduce them so equilibrium shifts to the right to produce more product
What happens to the equilibrium when you decrease the conc of a product?
system tries to increase the products so shifts to the right to oppose the change
How do you increase pressure?
decrease the volume by compressing gas in a syringe
What happens to the equilibrium when you increase the pressure of a reaction?
system wants to decrease the no. of mol sp equilibrium shifts to the side where there are fewer moles of gas
What happens to the equilibrium when you decrease the pressure of a reaction?
the system tries to increase the pressure by decreasing the no. of mol - shifts to the side with larger moles of gas
What colour is dichromate ions?
orange
What colour are chromate ions?
yellow
What does a catalyst do to equilibrium?
causes NO shift but speeds up the forward reaction so reached equilibrium sooner
What do you need to discuss on conditions for industrial processes for full marks?
- effect on equilibrium yeild - le chat
- effect on ROR - collision theory
- cost and safety
What is an industrial process that is an example of balancing equilibrium?
the haber process
What is the symbol for the equilibrium constant?
Kc
How can you tell if the equilibrium shifts to the right from kc value?
the bigger the Kc value - the further to the right the equlibrium position
if the Kc value is bigger than 1
What is the collision theory?
for a reaction to occur, molecules need to collide
What does the collision theory state that molecules need to react?
the correct molecular orientation
molecules must physically collide
molecules must have enough energy to break and form bonds
What does it mean by the correct molecular orientation?
attacking the oppositely charged side of a molecule = electrostatic attraction causes molecules to collide
What does the area under the boltzmann distribution curve represent?
the total no. of molecules in the system
Why doesn’t the boltzmann distribution curve never touch the x axis?
there is no maximum energy that molecules can have
Explain the effect of using a catalyst has on a reaction using the boltzmann distribution curve
the Ea is lowered therefore larger proportion of molecules are above the Ea
What is the effect of increasing temp on the boltzmann distribution curve ( the curves shape)?
the area under the curve is the same
the curve shifts to the right
the height of the peak falls
What are the 2 effects of increasing temp on a reaction using the boltzmann distribution curve?
- molcules have more KE so there is an increased frequency of collisions
- the no. of molecules with energy higher than the Ea has increased substantially, so there is a greater proportion of collisions that are successful
