Given : aligned & H _ sub ^ [ C ( graphite )]=710 ~kJ ~mol ⁻¹ & _ C - H H ^ =414 ~kJ ~mol ⁻¹ & _ H - H H ^ =436 ~kJ ~mol ⁻¹ & _ C = C H ^ =611 ~kJ ~mol ⁻¹ aligned The H _ f ^ for CH ₂= CH ₂ is _____ kJ mol ⁻¹ (nearest integer value)

Step-by-step solution

aligned & [ H _ f ^ o ]_ C ₂ H _ (4) =2 [ H _ sub ^ o ]_ C _ ( s ) +2 H _ H - H ^ o -1 H _ C = C ^ o -4 H _ CH ^ o & [ H _ f ^ o ]_ C ₂ H _ 4( ~g ) =(2 710)+(2 436)-611-4 414 & [ H _ f ^ o ]_ C ₂ H _ 4( ~g ) =25 ~kJ / mol aligned