Suppose you are a chemical engineer working in a plant that produces hydrogen iodide and are exploring the efficiency of the production process. If you know the value of K, for any given composition you can predict in which direction the reaction has a tendency to go. A mixture of hydrogen and iodine, each at 55 kPa, and hydrogen iodide, at 78 kPa, was introduced into a container heated to 783 K. At this temperature, K = 46 for H₂(g) + l₂(g) ⇌ 2 HI(g). Predict whether HI has a tendency to form or to decompose into H₂(g) and I₂(g).

PLAN Calculate Q and compare it with K. If Q > K, the products have a tendency to decompose into reactants until their concentrations match K. The opposite is true if Q < K; in that case, the reactants have a tendency to form more products.