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

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.