Question

Phosphorous pentafluoride (PF5) gas decomposes into phosphorous (P4) gas and fluorine (F2) gas at a certain temperature. Determine the equilibrium constant for this reaction at this temperature if the measured equilibrium concentrations ([ ](eq)) are: [PF 5)(eq) = 0.0198 M, [P4(eq) = 0.317 M, [F2](eq) = 0.744 M. Hint: You should write a balanced chemical equation for the reaction described. 2.37 x 107 1.07 x 105 8.41 x 10-2 1.85 x 10-7 11.9

Answer 1

4 PFs (9) [P4] eq? = 0.317 M 10 Keqi (0) P4 (9) +10 f2 Constant temperature (PF]eq = 0.0198M, [F2 Jeq = 0.744M [P4] a [f]" [pfs] 4 (0.317) x (0.144)' 0.01647 10-0198) 4 keq 106,948.05 keq = 1.069 610 1.069 x10~ 1.09x105 Equilibrium Conustaut (keq) = 1.09 x 105 10 0.000000154

Given 2IF (9) ► [2(g) + F2 (g) 0 Kpz 19.7 initial 0.306 0 P 00 90 At Eq. 0.306-22 Pr = 0-306-2x + 2x -0.306 Piz. Pfz x2 >kp= (0.306-2x)? 2 n » Kp² 0.306-22 2 X → 19.144 = 0.306-22 1 19.17 = 4.438 0.306-2x → X = (0.306-24) (4.438) 5 = 1.358 - 8876 a → 9.8176x2 1.358 0.1375 > 10 1.358 g. 876 ~ 1= 0-1375 atm Partial pressure of ff at équilibrium = 0.306 - 2x =[0-306- 2 x 0-1345/4 (am

- [ Pop) en 0.0310 atm (0.306-0.275) atm so Equilibrium partial pressure of If 0.0310 atm