Phosphorus pentachloride decomposes according to t...

Question

Phosphorus pentachloride decomposes according to the chemical equation.

PCl₅(g)⇌ PCI₃(g) + Cl₂(g) K_c = 1.80 at 250 °C

A 0.250 mol sample of PCl₅(g) is injected into an empty 2.50 L reaction vessel held at 250 °C. Calculate the concentrations of PCl₅(g) and PCl₃(g) at equilibrium.

Jules Bruno · Accepted Answer

We are asked to calculate the equilibrium concentration of PCl5(g) and PCl3(g)We’re given the following equilibrium reaction:PCl5(g) ⇌ PCl3(g) + Cl2(g);    Kc = 1.80 at 250°CWe know that the initial amount of PCl5 is 0.250 mol. In a 2.50 L container, the concentration of each is:Molarity (M)=moles of soluteL of solutionMPCl5=0.250 mol2.50 LMPCl5 = 0.1[readmore]From this, we can construct an ICE table:The Kc expression for the reaction is:Kc=[products][reactants]=[PCl3][Cl2][PCl5]Note that each concentration is raised by the stoichiometric coefficient: [PCl5], [PCl3] and [Cl2] are raised to 1. Determine if x is negligibleinitial concentrationK=0.101.8=0.056Since x is less than 5, it cannot be neglected in the equilibrium expression.Plugging in the equilibrium pressures from the ICE table into the Kc expression:Kc=1.80=PCl3Cl2PCl51.80=(x)(x)(0.10-x)1.80×(0.10-x)=x2x2+1.80x-0.180=0x=-b±b2-(4×a×c)2ax=-1.80±(1.80)2-(4×1×(-0.180))2×1x=-1.80±3.24-(-0.72)2x=-1.80+3.962=0.095x=-1.80-3.962=-1.89Since we cannot have a negative value for x, we will use x = 0.095 MFrom the ICE table, we can see that the concentration of PCl5 and PCl3 at equilibrium are:[PCl5] = 0.10 M– x[PCl5] = 0.10 M– 0.095 M[PCl5] = 0.005 M[PCl3] = x[PCl3]  = 0.095 MThe concentration of PCl5 and PCl3 at equilibrium are 0.005 M and 0.095 M, respectively.

Problem: Phosphorus pentachloride decomposes according to the chemical equation.PCl5(g) ⇌ PCI3(g) + Cl2(g) Kc = 1.80 at 250 °CA 0.250 mol sample of PCl5(g) is injected into an empty 2.50 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.

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Problem: Phosphorus pentachloride decomposes according to the chemical equation.PCl5(g) ⇌ PCI3(g) + Cl2(g) Kc = 1.80 at 250 °CA 0.250 mol sample of PCl5(g) is injected into an empty 2.50 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.

FREE Expert Solution

Problem Details

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