Chemical Equilibrium II Tutorial

Tutorial for Experiment: Chemical Equilibrium II

EXAMPLE: If 8.0 moles of A and 6.0 moles of B are placed initially in a 2.00 L container at 25ºC, what will be the change in moles and the equilibrium moles of A, B, and C?

EXPERIMENT: Place 8.0 moles of A and 6.0 moles of B in a 2.00 L container at 25ºC and monitor the progress of the reaction with the plots of molarity versus time. Record the equilibrium molarities (mol/L) of A, B, and C.

PROCEDURE:

  1. The initial molarity of A is



    Enter 4.0 for the initial molarity of A in the box labeled "[A]."



  2. Enter 3.0 for the initial molarity of B in the box labeled "[B]" and 0.0 for the initial molarity of C in the box labeled "[C]."



  3. Enter 298 (273 + 25ºC) in the box labeled "Temp(Kelvin)."



  4. Click the "Enter" button to display the plots of molarity versus time. Record the equilibrium molarities of A, B, and C.





RESULTS and OBSERVATIONS: The equilibrium molarities of A, B, and C are



and the moles of A, B, and C at equilibrium are



   To determine the change in moles ofA, B, and C, create an equilibrium table.



Since

then

and


The changes in the moles of A and B are proportional to the change in moles of C. The proportationality constants that the change in moles of C is multiplied by to obtain the changes in moles of A and B are the mole ratios.


and


The changes in the moles of A and B appear in the equilibrium table as negative numbers because moles of A and B are consumed as the reaction proceeds to equilibrium.