AP Chemistry Unit 7

Equilibrium is a (blank), low-energy state that reversible reactions tend toward

Stable

Haber process, which is used in the (blank)

preparation of ammonia

Equilibrium does NOT mean the (blank) has stopped or that the concentrations of the reactants and products (blank)

• stopped

• equal

The relationship between the concentration of reactants and products is given by the (blank)

Equilibirum

Equilibrium Expression

[C]^c[D]^d / [A]^a[B]^b

The value of the equilibrium is the (blank)

Equilibrium constant, K_eq

If Keq > 1 then the (blank) is larger; the products are (blank), meaning more (blank) are present

• numerator

• favored

• products than reactants

If Keq < 1 then the (blank) is larger; the reactants are (blank)

• denominator

• favored at equilibrium

Kc constant

Molar concentrations

Kp constant

Partial Pressure

Ksp constant

solubility product

Ka constant

acid dissociation for weak acid

Kb constant

base dissociation for weak bases

Kw constant

ionization of water (kw = 1 x 10^-14)

How to manipulate Keq for reactions

1. Reverse a reactions, take the reciprocal of its equilibrium constant to get the new constant

2. If you multiply a reaction by coefficient, raise the equilibrium constant to the power of that coefficient to get the new one

3. If you add two reactions together, multiply their equilibrium constants to get the new one

The reaction quotient, Q, can be calculated by (blank)

• plugging concentrations from any point in the reaction into the equilibrium expression

Keq changes with (blank)

temperature

Q changes with (blank)

• concentration

• pressure

• temperature

If Q = Keq then reaction is at (blank) and no (blank)

• equilibrium

• no change will occur

If Q > Keq, the numerator is larger than it should be equilibirum, then there is an (blank) of products and the reaction must proceed in the (blank)

• excess

• reverse

if Q < Keq, then there is an (blank) of the reactants and the reaction much proceed (blank)

• excess

• forward

(blank) states that whenever a stress is placed on a system at equilibrium, the system will shift to (blank) that stress to restore (blank)

• Le Chatelier’s Principle

• reduce

• equilibrium

If the forward rate (blank), the reaction shifts (blank) and makes more products

• increases

• right

If the reverse rate (blank), the reaction shifts (blank) and more reactants are created

• increases

• left

When some reactant or product is added, the reaction will shift in the (blank) that allows it to use up the added substances

• direction

• Ex: if N₂ is added, the reaction shifts right and if NH₃ is added the reaction shifts left

When the external pressure on a container is increased, that will increase the partial pressures of all the gases inside. To restore equilibrium, these partial pressure must (blank)

• decrease

• and decreasing the partial pressure of gases would have the opposite effectIn

Increasing volume would (blank) those partial pressures and cause a shift to the side with (blank)

• decrease

• more gas molecules

If you add a (blank) to a sealed, rigid container with a fixed volume, the partial pressures of the other gases are (blank)

• Noble gas

• not affected

Decreasing volume or removing a noble gas at constant pressure would cause a shift to the side with (blank)

• fewer gas molecules

• the opposite will shift to the side with more particles

If a noble gas is added at constant volume, only the total (blank) changes while partial pressures don’t

pressure

Adding some water to an aqueous reaction will (blank) the concentration of all dissolved species

decrease

If there are different numbers of aqueous species on either side of the reaction, the dilution cause a shift to the side with (blank)

more aqueous species

If you were to dilute the reaction above at equilibrium, it would shift (blank)

left to favor two aqueous ions over one

• if concentrated it would shift right

Exothermic Process

If the temperature is increased, the reaction will use up the added energy and shift (blank). if the temperature is decreased the reaction will shift (blank)

• left

• right

• the reverse is true for an endothermic process

At higher temperature, the (blank) will be favored more than they are at lower temperatures

Reactants

Soluble salts are assumed to (blank)

dissociate completely in aqueous solution

The (blank) is a measure of the extent of a salt’s dissociation in the solution

Solubility Product (K_sp)

The greater the (blank) of the solubility product, the more (blank) the salt

• value

• soluble

The molar solubility of the salt will also be equal to the concentration of (blank) that occurs in a 1:1 stoichiometric ratio

any ion

When two salt solutions that share a common ion are mixed, the salt with the (blank) for K_sp will precipitate first

lower value