Chemical Systems and Equilibrium

Learning Goals:

• Explain the concept of dynamic equilibrium, using examples of physical and chemical equilibrium systems.

• Explain the concept of chemical equilibrium and how it applies to the concentration of reactants and products in a chemical reaction at equilibrium.

• Create and complete an ICE table for an equilibrium system.

• Draw graphs of c vs. t to illustrate a chemical system approaching equilibrium.

• Use appropriate terminology such as dynamic equilibrium, reversible reaction, closed system, equilibrium concentrations, phase equilibrium, solubility equilibrium, chemical equilibrium, equilibrium position

Dynamic Equilibrium• rate of forward reaction = rate of reverse reaction• an observable macroscopic property remains constant

How do the following images represent

dynamic equilibrium?

Dynamic Equilibrium?•two kids balanced on a teeter-totter•player substitutions during a hockey game•outdoor pool•indoor pool•your own idea?

summer haze

Consider the following…

Over time, what happens to an open beaker of water?

Over time, what happens to the water level if we cover the beaker?

We can study equilibrium under closed systems!

Write an equation to describe the equilibrium system.

What conditions are required for a dynamic equilibrium to exist?

• reaction is reversible• closed system

What are the key characteristics of a dynamic equilibrium?

• forward rate = reverse rate• observable macroscopic property remains constant

3 types of Equilibrium

1. Solubility Equilibrium 2. Phase Equilibrium3. Chemical Equilibrium

NaCl(s) Na+ (aq) + Cl- (aq)

Chemical Equilibrium

Write an equation to describe this equilibrium system.

Initially, N2O4(g) is in the flask. Draw a graph to illustrate the changes in concentration of R and P as the system approaches equilibrium.

Does slope = 0 mean the reaction has stopped?

Are the concentrations of R and P equal at equilibrium?