# Chapter 12: equilibrium

## 17 terms

### equilibrium constant (K)

A number characteristic of an equilibrium system at a particular temperature.

### equilibrium expression

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

### coefficient rule

If the coefficients in a balanced equation are multiplied by a factor n, the equilibrium constant is raised to the nth power.

### reciprocal rule

The equilibrium constants for forward and reverse reactions are the reciprocals of each other.

### multiple equilibria rule

If a reaction can be expressed as the sum of two or more reactions, K for the overall reaction is the product of the equilibrium constants of the individual reactions.

### La Châtelier's principle

Whenever a stress is applied to a system at equilibrium, the equilibrium will shift to relieve that stress and reestablish equilibrium.

### van't Hoff equation

ln K₂/K₁=ΔH°/R [1/T₁-1/T₂]

### The Reaction Quotient (Q)

Used to determine reaction direction.

### Q<K

the reaction proceeds in the forward direction, generating products.

### Q>K

the reaction proceeds in the reverse direction, generation reactants.

### Q=K

the reaction is already at equilibrium.

(-b±√b²-4ac)/2a

### equilibrium

A state of dynamic balance between forward and reverse reactions that does not change with time.

### K>1

products form. (spontaneous reaction)

### K<1

reactants need additional assistance to form products. (nonspontaneous).

### K=1

equilibrium mixture contains equal amounts

Kp=Kc(RT)^n(gas)