Chemical Equilibria Flashcards
What two things happen in a reversible reaction
• Forward and reverse reactions proceed at equal rates
• The concentrations of reactants and products remain constant
How does a catalyst affect affect the position of equilibrium?
It does not
What is the expression for Kc
Products/ reactants
Dynamic equilibrium is reached when:
• The rate of forward reaction is equal to the rate of backward reaction
• Concentration of both the products and reactants is constant
What factors alter the position of equilibrium?
• Temperature
• Pressure
• Concentration
• Amount of substance
What type of system does equilibrium take place in ?
A closed system
A bigger amount of products means what?
A bigger yield
Why don’t catalysts affect the position of equilibrium?
A catalyst provides an alternative pathway to lower the activation energy
What is le chataliers principle?
If a system (reversible reaction) is in equilibrium, if any condition is changed, the system will shift in such a direction to oppose the change and restore equilibrium
What does COSY stand for?
C- Change in conditions
O- Opposition to the change
S- Shift to oppose the change
Y- The equilibrium yield of the product
What equation is helpful in determining the effect of increasing/ decreasing temperature/pressure
N2 + 3H2 -> 2NH3(g) = -92 kj mol
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What is the effect of increasing the concentration of reactants on a reaction at equilibrium?
• Reactants increased
• Oppose the change
• Shift to RHS
• Yield increases
What is the effect of increasing the concentration of the products on a reaction at equilibrium
• Products increased
• Oppose the change in the products
• Shift to the left hand side
• The yield increases
What is the effect of removing the products from a reaction at equilibrium
• Product removed
•Oppose the change in productions
• Shift of equilibrium to the right hand side
• the yield will increase
What is the effect of increasing the pressure on a reaction at equilibrium
• Increase in pressure
• Oppose the increase in pressure
• Shift to the area with less moles
• either the yield will increase/decrease
What is the effect of decreasing the pressure on a reaction at equilibrium
• Decrease in pressure
• Oppose the decrease in pressure
• shifts to the area with more moles
• Either the products will increase or decrease
What is the effect of increasing the temperature on an endothermic reaction at equilibrium
• Increase the temperature
• Oppose the increase in temperature
• Shifts to the right hand side
• Increase the yield
What is the effect of decreasing the temperature on an endothermic reaction at equilibrium
• Decrease in temperature
• Oppose in decrease in temperature
• Shifts to the left hand side
• Decrease in the yield
What is the effect of increasing the temperature on an exothermic reaction at equilibrium
• Increase in temperature
• Oppose in the increase in temperature
• Shift to the left hand side
• Decrease in yield
What is the effect of decreasing the temperature on an exothermic reaction at equilibrium
• Decrease in temperature
• Oppose the decrease in temperature
• Shifts to the right hand side
• Increase in yield more products
I’m industry, making the highest possible yield of products quickly and cheaply leads to a what?
Compromise between the reaction rate and chemical equilibrium
What is the formula for Kc
Products/reactants
How is Kc calculated?
Using Concentration of products and reactants
What effect does increasing the pressure have on the rate of reaction?
- Increasing the pressure will increase the rate of reaction
- At a high pressure, there will be more oxygen molecules in a given volume/ the molecules will be pushed together
- so, collision between the molecules is more likely
- More collisions mean more successful and frequent collisions and a higher rate of reaction
What is the effect of a catalyst on the number of molecules
- increases the number of molecules able to react
- lowers the activation energy by providing an alternative pathway
- meaning that more molecules will have sufficient energy to react
Give the units for the following reaction
• CH2=CH2(g) + H2O(g) equilibrium CH3CH2OH(g)
Mol-1dm3