Equilibrium

Front 1

Equilibrium

Back 1

a state in which both the forward and the reverse reactions continue to occur at equal rates so that no net change is observed

Front 2

K expressions and K constant

Back 2

units are never given with K

Front 3

importance of K constant

Back 3

- if ratio of products to reactants matches K value, system is at equilibrium. If ratio not equal to K value, system isn't in equilibrium.

Front 4

meaning of K constant

Back 4

- K>>1: Reaction is product favored. (concentration of products > concentration of reactants)
- K<<1: reaction is reactant-favored. (concentration of reactants > concentration of products)

Front 5

Reaction Quotient Q

Back 5

When system is not at equilibrium, reaction quotient can be calculated the same way as K value.

Front 6

meanings of Q

Back 6

- Q<K=reactants must be converted to products to reach equilibrium
- Q>K=products must be converted to reactants to reach equilibrium
- Q=K, then system is at equilibrium

Front 7

ICE table

Back 7

I=Initial concentrations
C=Change in concentrations as reaction proceeds to equilibrium
E=Equilibrium concentration

Front 8

Equilibrium Constant using partial pressures

Back 8

instead of using concentration (M), pressures of gaseous reactants and products can be used to calculate Kp of a reaction.
Value of Kp will be same as value of Kc (c=concentration) only when the # of moles of gaseous reactants is the same as products.

Front 9

Calculations involving Quadratic Equation

Back 9

If 100 x K < concentration of the reactants at equilibrium, then x on bottom of fraction can be omitted.

Front 10

Effects of raising stoichiometric coefficients

Back 10

If you raise coefficients of a balanced equation by some factor, the new K value is the old K value raised to the power of the multiplication factor.

Front 11

Effects of raising reversing reactions

Back 11

The equilibrium constants for a reaction and its reverse are the reciprocals of each other

Front 12

Effects of raising adding reactions

Back 12

When two or more chemical equations are added to produce a net equation, the equilibrium constant for the net reaction is the product of the equilibrium constants for the added equations

Front 13

Le Chatelier's Principle

Back 13

A change in any of the factors that determine the equilibrium conditions of a system will cause the system to change in such a manner as to reduce or counteract the effect of the change

Front 14

Ways to disturb equilibrium

Back 14

1. changing the temperature
2. changing concentration of reactant of product
3. changing the volume (for gases only)

Front 15

Temperature's effect on equilibrium

Back 15

- when temperature of system at equilibrium increases, equilibrium will shift in direction that absorbs heat (endothermic direction)
- if temperature decreases, equilibrium will shift in direction that releases heat (exothermic direction)

Front 16

Effect on equilibrium by addition of products or reactants

Back 16

- adding more products to reaction at equilibrium causes the reaction to shift toward reactants because more reactants must be produced to compensate for added products
- if reactants added, more products formed to compensate for added reactants.

Front 17

Volume effect on equilibrium

Back 17

- volume decrease leads to change in equilibrium composition to one having smaller number of molecules
- volume increase leads to change in composition of the side favoring the larger number of molecules
- for reactions in which there is no change of the # of molecules, volume change will have no effect.
(H2(g) + I2(g) <-> 2HI(g))