AP Chemistry · Unit 7: Equilibrium
7.3 Reaction Quotient and Equilibrium Constant
In short
You must be able to write expressions for the reaction quotient (Qc or Qp) and the equilibrium constant (Kc or Kp) using the law of mass action. You must understand that Qc describes relative concentrations at any time and tends toward Kc at equilibrium.
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What else do you need to know about Reaction Quotient and Equilibrium Constant?
Expressions must correctly omit solids and pure liquids, as their concentrations or partial pressures are independent of the amount present. The AP Exam explicitly excludes assessing the mathematical conversion between Kc and Kp, as well as equilibrium calculations on systems where a dissolved species is in equilibrium with that species in the gas phase.
How is Reaction Quotient and Equilibrium Constant tested on the exam?
Exam questions may use either Kc or Kp; you must be aware of the conceptual differences and pay close attention to which is being used in a given question. The associated skill (3.A) indicates you may be asked to represent chemical phenomena using appropriate graphing techniques, including correct scale and units.
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Reaction Quotient and Equilibrium Constant: common questions
What do you need to know about Reaction Quotient and Equilibrium Constant for AP Chemistry?
You must be able to write expressions for the reaction quotient (Qc or Qp) and the equilibrium constant (Kc or Kp) using the law of mass action. You must understand that Qc describes relative concentrations at any time and tends toward Kc at equilibrium.
How is Reaction Quotient and Equilibrium Constant tested on the AP Chemistry exam?
Exam questions may use either Kc or Kp; you must be aware of the conceptual differences and pay close attention to which is being used in a given question. The associated skill (3.A) indicates you may be asked to represent chemical phenomena using appropriate graphing techniques, including correct scale and units.
Where does Reaction Quotient and Equilibrium Constant fit in AP Chemistry?
Reaction Quotient and Equilibrium Constant is topic 7.3 in Unit 7: Equilibrium of AP Chemistry.
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