Chapter 6, Problem 62P

Consider the following reaction.
   ${\text{H}}_{\text{2}}(g){\text{ + I}}_{\text{2}}(g)\stackrel{}{\rightleftarrows }\text{ 2 HI}(g)$
a. Write the expression for the equilibrium constant.
b. Calculate $K$ using the following concentrations of each substance at equilibrium:
   $[{\text{H}}_{\text{2}}]\text{ = 0}\text{.95 M; }[{\text{I}}_{\text{2}}]\text{ = 0}\text{.78 M; }[\text{HI}]\text{ = 0}\text{.27 M}\text{.}$