Question

A student attempts a chemical reaction in the laboratory. The student is successful in obtaining a small amount of the desired product. However, most of the reactants just "sit there" in the reaction container. What can we assume about the value of the equilibrium constant for this reaction?

a) The equilibrium constant is a very, very small decimal number.

b) The equilibrium constant is fairly small, perhaps a bit below 1.

c) The equilibrium constant is fairly large; perhaps a bit above 1.

d) The equilibrium constant is very, very large - it's over 1,000.

Answer 1

Option A.  The equilibrium constant is a very, very small decimal number.

Explanation:

The equilibrium constant K, expresses the relationship between products and reactants of a reaction at equilibrium with respect to a specific unit.

If we have a reaction like:

A + B <--------> C + D

K = [Products] / [Reactants]

K = [C] [D] / [A] [B]

So, if concentrations of C and D > A and B means that the products are predominant in the reaction, and this will cause that the reaction is favorized to the formation of products, and the numerical value of K will be >1.

If [Reactants] > [Products] means that A and B are predominant and it's not forming so well the products. The reaction will go to the left instead of the formation of products, so the K value will be <1.

As you are getting most of the reactants in this reaction, you can assume that the value of K is very low so you can have a large amount of reactants.

Hope this helps