Problem

A student places equal numbers of moles of

\text{SO}_{2}(g)

and

\text{SO}_{3}(g)

into a rigid container at constant temperature, allowing the system

\displaystyle 2\text{SO}_{3}(g)\rightleftharpoons 2\text{SO}_{2}(g)+\text{O}_{2}(g)

to reach equilibrium. After equilibrium is established, additional

\text{SO}_{3}

is found to form spontaneously. Which statement best explains how the value of

Q_{p}

for the initial mixture compares with

K_{p}

for the reaction? a)

Q_{p}=K_{p}

because equal initial amounts of

\text{SO}_{2}

and

\text{SO}_{3}

indicate that the system started at equilibrium. b)

Q_{p}<K_{p}

because the reaction proceeded in the direction that consumes

\text{SO}_{3}

to reach equilibrium. c)

Q_{p}>K_{p}

because the reaction shifted toward the reactants to reach equilibrium. d)

Q_{p}>K_{p}

because the absence of

\text{O}_{2}

made the denominator of the

Q_{p}

expression larger than the numerator.