Question

Calculating an equilibrium constant from a heterogeneou... Nitrogen dioxide and water react to form nitric acid and nitrogen monoxide, like this: 3 NO2(9)+H2O(1)-2 HNO3(aq)+NO(9) At a certain temperature, a chemist finds that a 9.3 L reaction vessel containing a mixture of nitrogen dioxide, water, nitric acid, and nitrogen monoxide at equilibrium has the following composition: compound amount NO 24.18 HO 247.2 g HNO, 7.4 g NO 17.6 Calculate the value of the equilibrium constant for this reaction. Round your answer to 2 significant digits. x 5 ?

Answer 1

Moles of NO2 = Mass/molar mass = 24.1/46 = 0.5239

Moles of HNO3 = 7.4/63 = 0.1175

Moles of NO = 17.6/30 = 0.5867

[NO2] = 0.5239/9.3 = 0.05633 M

[HNO3] = 0.1175/9.3 = 0.01263 M

[NO] = 0.5867/9.3 = 0.0631 M

Kc = [HNO3]^2 * [NO] / [NO2]^3

Kc = (0.01263)^2 * (0.0631) / (0.05633)^3

Kc = 0.0563 OR 0.056    ....Answer

Let me know if any doubts.