9-Chemical Equilibria

what is the equation for equilibrium constant for conc?

Kc = [products]/[reactants]

-where you make the coefficients into exponents

equilibrium reaction rates constants depend on ONLY the reaction's coefficients and not the mechanism

only a change in temperature can change equilibrium constant, k

only aqueous or gaseous states are included in equilibrium expression

what is the equation for equilibrium constant for pressure?

Kp = Pproducts/Preactants

only aqueous or gaseous states are included in equilibrium expression

how do you figure out the Kc of the reverse reaction if you know the Kc of the forward reaction?

take the reciprocal

what does it mean if K is more than 1?

products are favored at eq.

what does it mean if K is less than 1?

reactants are favored at eq.

in an experimental setting where you measure the levels of products and reactants at a specific point during the reaction, what does it mean if Q (the experimental value) is less than K?

you must shift the reaction to the right to reach equilibrium

in an experimental setting where you measure the levels of products and reactants at a specific point during the reaction, what does it mean if Q (the experimental value) is more than K?

you must shift the reaction to the left to reach equilibrium

in an experimental setting where you measure the levels of products and reactants at a specific point during the reaction, what does it mean if Q (the experimental value) is equal to K?

the reaction is at equilibrium

if a system at equilibrium is disturbed, then it will shift in whichever direction it has to to restore equilibrium

Le Chatelier's Principle

only applies to aqueous or gaseous compounds!

if a reaction is exothermic (-delta H), how do we treat heat in Le Chatelier's principle?

you treat heat like a product since exothermic reactions give off heat

if a reaction is endothermic (+delta H), how do we treat heat in Le Chatelier's principle?

you treat heat like a reactant since endothermic reactions consume heat

when pressure is increased or volume is decreased, how will reactions shift in Le chatelier's principle to restore eq?

Eq. reactions will shift in whichever direction reduces the number of gas molecules or the side that has the fewest gas molecules

how will a reaction of gases shift if you add an inert gas? (a gas that isn't involved in the reaction)

there will be no shift because the inert gas doesn't participate