Question

Phosphorous pentachloride decomposes according to the reaction PCI;(g) =PC12(g) + Cl2(g) A 15.7 g sample of PCI, is added to a sealed 1.25 L flask and the reaction is allowed to come to equilibrium at a constant temperature. At equilibrium, 48.6% of the PCI, remains. What is the equilibrium constant, K., for the reaction? K =

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Answer 1

To calculate the equilibrium constant, K, for the reaction PCI; (g) =PC12(g) + Cl2(g), we first need to determine the concentrations of the reactants at equilibrium. Given that 48.6% of the PCI remains at equilibrium, we can calculate the concentration of PCI as 0.0368 M. The equilibrium constant, K, is equal to 0.0368.

Step-by-step explanation:

To calculate the equilibrium constant, K, for the reaction between phosphorous pentachloride (PCl5) and chlorine gas (Cl2), we first need to determine the concentrations of the reactants at equilibrium.

Given that 48.6% of the PCl5 remains at equilibrium, we can calculate the concentration of PCl5 as follows:

Concentration of PCl5 = 48.6% × initial concentration of PCl5 = 0.486 × 15.7 g / (molar mass of PCl5) = (0.486 × 15.7 g) / (208.21 g/mol) = 0.0368 M

Since PCl5 decomposes into PCl3 and Cl2, the concentrations of PCl3 and Cl2 at equilibrium will be the same as the concentration of PCl5 (0.0368 M).

Therefore, the equilibrium constant, K, can be calculated using the concentrations of PCl5, PCl3, and Cl2:

K = [PCl3] × [Cl2] / [PCl5] = (0.0368) × (0.0368) / (0.0368) = 0.0368