# AP Objectives Of Equilibrium

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Students will be able to:

1) Explain what a reversible reaction is and the conditions for equilibrium to be established. This explanation can be via graphs, pictures and/or prose.

2) Explain the concept of Reaction Quotient (Q) and how it relates to the Equilibrium constant, K to explain how the reaction proceeds to the equilibrium condition (is reaction going to produce more reactant/products). Explanation can via graphs, pictures and/or prose.

3) Using a desired balanced reversible chemical equation including phase, write out the Equilibrium constant expression including showing any species removed from expression due to being a solid and/or liquid. An explanation of this removal needs to be stated.

4) Explain what the qualitative explanation of the Equilibrium constant (K) means with respect to determining the equilibrium position (equilibrium concentration for all species in reversible reaction) including what conditions change K.

5) Using calculated value of Q and K to explain how the reaction will proceed (making more product or reactant) to equilibrium (see Objective 2 above).

6) Given a balanced reversible reaction and it Equilibrium constant value, be able to determine the Equilibrium constant value, K' of a related balanced chemical reaction (i.e. the original reaction is reversed, what is K' compared to original reaction K).

7) When the system uses partial pressures instead of concentration in the problem, be able to do all task except it is Kp instead of K. For 2019-2020 student, do not have to be able to mathematical determine Kp from K information or visa versa.

8) Given a balanced reversible reaction, Equilibrium constant expression, mathematically determine the equilibrium position (i.e. all species concentrations at Equilibrium) and/or Equilibrium constant (K) using:
• Knowing all equilibrium constant, determine value of K (and its units)
• Knowing all equilibrium concentration except one and value of K, determine value of the unknown equilibrium concentration.
• Knowing initial information and one piece of equilibrium information ( [ ] or %, atm ), determine the equilibrium position and K. This will require that you use an ICE BOX (table of initial, change and at equilibrium information for each species).
• Knowing initial information and NO pieces of equilibrium information, value of K. This will require that you use an ICE BOX with "x" (table of initial, change and at equilibrium information for each species).
• Special case Knowing initial partial pressures and total pressure at equilibrium (Ptotal,E, determine the equilibrium position and value of Equilibrium constant (Kp).

9) State LeChatelier's Principle, and what it means with respect to the new equilibrium position compared to the original equilibrium position. For all stresses except temperature change, both qualitative explanation and mathematical manipulation of Equilibrium expression explanation can be determined.

10) Using LeChatelier's Principle, be able to explain via the 4 step process used in notes/class to explain the shift in equilibrium / answer question as a result of the desired stress. Stress on equilibrium includes change in concentration of all reactant species, temperature change, add catalyst, change in volume, change in pressures.

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