### Video Transcript

The following equation describes
the reaction between different types of gases. Three W gas plus five X gas are in
equilibrium with four Y gas plus six Z gas. Which of the following expressions
can be used to determine the value of πΎ π for this reaction? (A) πΎ π equals πZ to the sixth
times πY to the fourth divided by πW times πX. (B) πΎ π equals πZ times πY
divided by πW to the third times πX to the fifth. (C) πΎ π equals πZ to the sixth
times πY to the fourth divided by πW to the third times πX to the fifth. (D) πΎ π equals πX to the fifth
times πY to the fourth divided by πW to the third times πZ to the sixth. (E) πΎ π equals πZ to the sixth
times πW to the third divided by πX to the fifth times πY to the fourth.

To answer this question, we must
determine an expression that can be used to calculate the value of πΎ π for the
given reversible reaction. πΎ π is the equilibrium constant
for partial pressures. The equilibrium constant for
partial pressures is the ratio between the partial pressures of the products and
reactants at equilibrium. To see how to calculate this
constant, letβs take a look at a generic reaction equation.

In this equation, the lowercase
letters represent stoichiometric coefficients and the uppercase letters represent
chemical formulas. To construct an equation for the
equilibrium constant for partial pressures, we write the partial pressures of the
products, C and D, in the numerator and the partial pressures of the reactants, A
and B, in the denominator. Then, to complete the expression,
each individual partial pressure is raised to the power of the respective
stoichiometric coefficient.

Now that we have a generic
expression for πΎ π, we can apply our understanding to the reaction equation given
in the question. To construct the πΎ π expression,
we write the partial pressures of the products, Y and Z, in the numerator. We write the partial pressures of
the reactants, W and X, in the denominator. Then, we raise each of the partial
pressures to the power of their corresponding stoichiometric coefficient. This is the correct expression for
πΎ π for this reaction.

The answer choice that best matches
the expression we have written is answer choice (C). The partial pressures of Y and Z
are in the numerator, and the partial pressures of W and X are in the
denominator. In addition, all of the partial
pressures are raised to the correct power. In conclusion, the expression that
can be used to determine the value of πΎ π for the given reaction is answer choice
(C). πΎ π equals πZ to the sixth times
πY to the fourth divided by πW to the third times πX to the fifth.