Problem PageQuestion Methanol and oxygen react to form carbon dioxide and water, like this: (l)(g)(g)(g) At a certain temperature, a chemist finds that a reaction vessel containing a mixture of methanol, oxygen, carbon dioxide, and water at equilibrium has the following composition: compoundamount Calculate the value of the equilibrium constant for this reaction. Round your answer to significant digits. Clears your work. Undoes your last action. Provides information about entering answers.

We write the equilibrium expression including the gaseous or aqueous species only, that is why the methanol is not included due to heterogeneous equilibrium:

[tex]Kc=\frac{[CO_2]^2[H_2O]^4}{[O_2]^3}[/tex]

Whereas each gaseous species is powered to its stoichiometric coefficient (number before the species). In such a way, considering the equilibrium masses of carbon dioxide (44 g/mol), water (18 g/mol) and oxygen (32 g/mol) to be 1.56 g, 2.28 g and 3.33 g respectively, we compute the moles as we need molar concentrations in the equilibrium constant calculation:

[tex]n_{CO_2}=1.56g/(44g/mol)=0.0355mol\\\\n_{H_2O}=2.28g/(18g/mol)=0.127mol\\\\n_{O_2}=3.33 g/(32g/mol)=0.104mol[/tex]

Thus, into the 9.3.L vessel, the equilibrium concentrations are:

[tex][CO_2]=\frac{0.0355mol}{9.3L}=0.00382M[/tex]

[tex][H_2O]=\frac{0.127mol}{9.3L}=0.0137M[/tex]

[tex][O_2]=\frac{0.104mol}{9.3L}=0.0112M[/tex]

Therefore, the equilibrium constant shown with two significant figures is:

[tex]Kc=\frac{(0.00382M)^2(0.0138M)^4}{(0.0112M)^3} \\\\Kc=3.8x10^{-7}[/tex]

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