The Reaction Quotient Video Lessons

Example

# Problem: Consider the reaction and its equilibrium constant: N2O4(g) ⇌ 2NO2(g); Kc = 5.85 x 10–3 (at some temperature)A reaction mixture contains [NO2] = 0.0251 M and [N2O4] = 0.0331 M. Determine the direction in which the reaction will proceed.

###### FREE Expert Solution

For this problem, we have to determine the direction in which the reaction will proceed.

N2O4(g) ⇌ 2 NO2(g)

Recall that the equilibrium constant is the ratio of the products and reactants. We use Kp when dealing with pressure and Kc when dealing with concentration:

$\overline{){{\mathbf{K}}}_{{\mathbf{p}}}{\mathbf{=}}\frac{{\mathbf{P}}_{\mathbf{products}}}{{\mathbf{P}}_{\mathbf{reactants}}}}$     $\overline{){{\mathbf{K}}}_{{\mathbf{c}}}{\mathbf{=}}\frac{\mathbf{\left[}\mathbf{products}\mathbf{\right]}}{\mathbf{\left[}\mathbf{reactants}\mathbf{\right]}}}$

Note that solid and liquid compounds are ignored in the equilibrium expression.

Since we’re given the concentration of each compound, we use Kc. The Kc expression for the reaction is:

$\overline{){{\mathbf{K}}}_{{\mathbf{c}}}{\mathbf{=}}\frac{\left[\mathrm{products}\right]}{\left[\mathrm{reactants}\right]}{\mathbf{=}}\frac{{\mathbf{\left[}{\mathbf{NO}}_{\mathbf{2}}\mathbf{\right]}}^{\mathbf{2}}}{\left[{N}_{2}{O}_{4}\right]}}$

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###### Problem Details

Consider the reaction and its equilibrium constant: N2O4(g) ⇌ 2NO2(g); Kc = 5.85 x 10–3 (at some temperature)

A reaction mixture contains [NO2] = 0.0251 M and [N2O4] = 0.0331 M. Determine the direction in which the reaction will proceed.