Phosphorus pentachloride is used in the industrial preparation of organic phosphorus compounds. Equation 1 shows its preparation from PCl3 and Cl2.
(1) PCl3(l) + Cl2(g) PCl5(s)
Use equations 2 and 3 to calculate ?H°rxn of equation 1.
(2) P4(s) + 6 Cl2(g) 4 PCl3(l)
?H = -1280 kJ
(3) P4(s) + 10 Cl2(g) 4 PCl5(s)
?H = -1774 kJ