Given overall reaction: P4 + 10Cl2 ---> 4PCl5 Delta H for the reaction = ?

PCl5 -----> PCl3 + Cl2 Delta H = +157 kJ

P4 + 6Cl2 ----> 4PCl3 Delta H = -1207 kJ

Calculate the Delta H for the overall reaction.

2 answers

P4+10Cl2>>4PCl3 + 4 Cl2 H=-1207kJ
4PCl3+4Cl2>>4PCl5 H=-157*4 kJ

total? add the two H
-5456