Consider the reaction: PCl3(g) + Cl2(g) PCl5(g). If [PCl3] = 0.78 M, [Cl2] = 0.44 M, and [PCl5] = 0.88 at equilibrium, what is the value of K?
A.0.39
B.1.4
C.2.6
D.0.72
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To determine the value of the equilibrium constant (K) for the reaction, we need to use the concentrations of the reactants and products at equilibrium.
The balanced chemical equation is: PCl3(g) + Cl2(g) -> PCl5(g)
The general equation for the equilibrium constant (K) is:
K = [products] / [reactants]
Thus, we need to calculate the ratio of the concentrations of the products to the concentrations of the reactants.
K = [PCl5] / ([PCl3] * [Cl2])
Plugging in the given values:
K = 0.88 / (0.78 * 0.44)
Calculating this expression:
K ≈ 2.572
Rounding this to the nearest tenth, we get:
K ≈ 2.6
The correct answer is therefore C. 2.6.
To find the value of K, we need to use the equilibrium concentrations of the reactants and products. The general equation for the reaction is:
PCl3(g) + Cl2(g) ⇌ PCl5(g)
The balanced equation tells us that the stoichiometric coefficient of PCl3 is 1, while the stoichiometric coefficients of Cl2 and PCl5 are both 1 as well.
Using the equilibrium concentrations, we can write the expression for K:
K = [PCl5] / ([PCl3] * [Cl2])
Substituting the given values:
K = 0.88 / (0.78 * 0.44)
Performing the calculations:
K = 0.88 / 0.3432
K ≈ 2.566
Therefore, the value of K is approximately 2.6, which corresponds to option C.
So, the correct answer is C.2.6.