Calculate ΔH for the following reaction: PCl3 (l) + Cl2 (g) → PCl5 (s)

given the following:

1) 2 P (s) + 3 Cl2 (g) → 2 PCl3 (l) ΔH = -639.4 kJ

2) 2 P (s) + 5 Cl2 (g) → 2 PCl5 (s) ΔH = -887.0 kJ

What is a substance? a. a physical property of matter b. a chemical property of matter c. an element or compound that cannot be physically separated d. characteristics used to tell the difference between mixtures