Short Answer 
The document outlines the chemical reaction involving carbon monoxide, hydrogen, and methanol, represented by CO (g) + 2 H2 (g) ‚áå CH3OH (g). It explains how to apply the law of mass action to establish the equilibrium constant expression, K_eq = [CO] [H2]^2 / [CH3OH], which describes the relationship between the concentrations of reactants and products at equilibrium.
Step 1: Understand the Reaction
In this system, we have a chemical reaction involving the following substances: carbon monoxide (CO), hydrogen (H2), and methanol (CH3OH). The reaction can be represented as: CO (g) + 2 H2 (g) ‚áå CH3OH (g). It’s crucial to note that all components are in the gaseous phase, making this a homogeneous equilibrium.
Step 2: Apply the Law of Mass Action
The law of mass action helps us express the equilibrium constant for this reaction. This law states that at equilibrium, the ratio of the concentration of products to reactants is constant. For our reaction, this is expressed in the form: Keq = [CO] [H2]2 / [CH3OH]. The concentration of hydrogen is squared because its stoichiometric coefficient in the balanced equation is 2.
Step 3: Write the Equilibrium Expression
The equilibrium expression incorporates the concentrations of the reactants and products at equilibrium. Thus, for our reaction, we can formally write: Keq = [CO] [H2]2 / [CH3OH]. This expression serves as a valuable tool for predicting the direction of the reaction under specific conditions and calculating the concentrations of the species involved.