# Chapter 15 - Priciples of Chemical Equilibrium - Exercises - Direction and Extent of Chemical Change - Page 690: 30

Since $Q_c \gt K_c$, the mixture is not at equilibrium, and the reaction will proceed in the reverse direction, toward reactants.

#### Work Step by Step

1. Calculate all the concentrations: $$[N_2O_4] = ( 0.0205 )/(5.25) = 0.00390 M$$ $$[NO_2] = ( 0.750 )/(5.25) = 0.143 M$$ - The exponent of each concentration is equal to its balance coefficient. $$Q_c = \frac{[Products]}{[Reactants]} = \frac{[ NO_2 ] ^{ 2 }}{[ N_2O_4 ]}$$ 2. Substitute the values and calculate the quocient value: $$Q_c = \frac{( 0.143 )^{ 2 }}{( 0.00390 )} = 5.20$$ Since $Q_c \gt K_c$, the mixture is not at equilibrium, and the reaction will proceed in the reverse direction, toward reactants.

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