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1.00 mol of PCl5 was sealed into an evacuated 1.00 liter flask andallowed to rea

ID: 677143 • Letter: 1

Question

1.00 mol of PCl5 was sealed into an evacuated 1.00 liter flask andallowed to reach equilibrium at some temperature, according to thereaction: PCl5 (g) <-> PCl3 (g) + Cl2 (g) It was found that 2.00% of the PCl5 has decomposed whenequilibrium was reached. what is the numerical value of Kc? A. 5.00x10-3 B. 4.08x10-4 C. 2.00x10-2 D. 4.10x10-2 E. 2.04x10-4 PCl5 (g) <-> PCl3 (g) + Cl2 (g) It was found that 2.00% of the PCl5 has decomposed whenequilibrium was reached. what is the numerical value of Kc? A. 5.00x10-3 B. 4.08x10-4 C. 2.00x10-2 D. 4.10x10-2 E. 2.04x10-4

Explanation / Answer

Given data Moles of PCl5 = 1.0 mol Volume = 1.0 L Molarity = 1.0mol/1.0 L                    = 1.0 M                                   PCl5 (g) <-> PCl3 (g) + Cl2 (g) Initial(M)              1.0               0               0 Change(M)          -x                  +x             +x Equi(M)              1.0-x              x                x    Given that    2.0 % of PCl5 has decomposed                    x = 1.0M *2/100                          = 0.02 M       [PCl5]eq= 1.0 -x M                    = 1.0 - 0.02 M                    = 0.98 M        [PCl3]eq= x = 0.02 M          [Cl2]eq= x = 0.02 M               Kc =  [PCl3]eq*  [Cl2]eq /[PCl5]eq                        = 0.02M *0.02 M / 0.98M                        = 4.08*10-4    Hence option B is correct.    Hence option B is correct.