Chemical Equilibrium Flashcards
At equilibrium are the concentrations equal?
No, they are constant, not necessary equal
What is equilibrium?
When the rate of the forward reaction equals the rate of the reverse reaction.
What is Keq?
Equilibrium constant.
Concentration of the products over concentration of the reactants
What happens when Keq is greater than 1?
System favours the products
What happens when Keq is less than 1?
System favours reactants
What happens when Keq equals 1?
Concentration of products equals concentration of reactants
What is the mass action expression?
The concentration of the products raised to their coefficients over the concentration of the reactants raised to their coefficients
What can enter the mass action expression?
Only aqueous and gas forms
What is the reaction quotient?
Represented by Qc. Calculated by substituting the initial concentrations of the reactants and products into the equilibrium constant expression.
What happens when Qc is less than Kc?
Reaction proceeds left to right to establish equilibrium
What happens when Qc equals Kc?
System is at equilibrium
What happens when Qc is greater than Kc?
Reaction proceeds right to left in order to establish equilibrium
How do you calculate Keq?
Use the mass action expression. You may have to rearrange, set up an ice table, use variables, factor, use the quadratic formula and or the 500 rule
How do you set up an ice table?
Initial concentration
Change in concentration
Equilibrium concentration
What is the 500 rule check?
Take the initial concentration of reactant and divide by Keq. If this number is greater than 500, you can eliminate x in the denominator.
What is le chateliers principle?
If am outside influence upsets and equilibrium, the system responds in a direction that counteracts the disturbing influence so that the equilibrium is re-established
What factors affect equilibrium?
Temperature, pressure, catalyst, addition of reactant or product, addition of inert
How does the system react to change in temperature?
Shifts to make more heat, or use up excess heat
How does the system react to change in pressure?
If there is a decrease in pressure, shift to the side with more molecules
If there is an increase in pressure, shift to the side with fewer molecules
How does the system react to a catalyst?
Causes equilibrium to be reached at a faster rate
How does the system react to an addition of reactant or product?
Shift to side to use up excess
How does the system react to a removal of react or product?
Shift to side to make more
How does the system react to an addition of an inert?
No effect because it will collide equally with reactants and products
What is the only factor that affects Keq? What relationship is maintained?
Temperature
Exothermic=inversely proportional
Endothermic=directly proportional
What is the haber process?
To increase the amount of products made, the product is condensed and removed, never allowing the reaction to reach equilibrium
What is solubility equilibrium?
Equilibrium that exists between and ionic solid (that has been dissolved in water) and its ions in solution
What is ksp?
Solubility constant, indicates how soluble a substance is. Ksp is equal to the product of the concentration terms each raised to the power of the coefficients of the substance in the dissociation equation.
Low=not very soluble
High=soluble
What is dynamic equilibrium?
All parts of the system are constantly moving in opposite directions at equal rates so that the system as a whole does not change
