Study Sheet

Study Sheet

Sample Study Sheet: Calculating Equilibrium Pressures   

Tip-off You are asked for the equilibrium partial pressures of reactants and products, and you are given the equation for the reaction, its KP (or a table of KP values), and the initial partial pressures of reactants.

General Steps

  • Write the equilibrium constant expression that corresponds to the chemical equation.
  • Set up a table for displaying the initial pressures, the changes in pressure, and the equilibrium pressures.

For our examples, assign x to the decrease in pressure of each reactant. The equilibrium partial pressure of each reactant will be the given initial partial pressure minus x. The equilibrium partial pressure of product will be x for reactions that have the first general form below or 2x for reactions that have the second form.

A(g)  +  B(g)        C(g)  +  D(g)

or      A(g)  +  B(g)        2C(g)

  • Plug the equilibrium concentration terms into the equilibrium constant expression.
  • Solve for x.
  • Use x to calculate the equilibrium concentrations of reactants and products.  

Click here to see an example. 

Click here to see an exercise that will allow you to try this task yourself. 

Return to the Equilibrium Calculations Page.

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