Introduction to Equilibrium

Introduction to Equilibrium

• Is this stationary or dynamic?

  dynamic

  ---

• There is no net change

Understanding Equilibrium

• In the bottle below, CO2 gas is leaving the dissolved state and entering the gas state
• At the same time, CO2 gas state is leaving the gas state and entering the liquid state
• $$CO2(g) ⇌ CO2(aq)

• There is no visible change while this is happening
• There are no (macroscopic/microscopic)

  macroscopic

  ---

  changes, but there are (macroscopic/microscopic)

  microscopic

  ---

  changes
• Review: is the above picture showing an open system, closed system, or isolated system?

  Closed

  ---

3 Types of Equilibrium

• This is specifically when we have a dynamic equilibrium between a solute and solvent
• ex: I2(s) ⇌ I2(aq)

• This is also called a saturated solution because it contains the maximum amount of a solute. If we tried to add more solute, it will remain in the solid form and won't dissolve.
• This is how we get a precipitate like the one below in solution!
• When a precipitate forms, it is called a supersaturated solution

• This is when we have a dynamic equilibrium between different physical states of a pure substance
• What is the phase equilibrium that is happening in the picture below?

• H2O(l) ⇌ H2O(g)

• This is when we have a dynamic equilibrium between reactants and products of a chemical reaction
• ex. N2O4(g) ⇌ 2NO2(g)