An important industrial source of ethanol is the reaction, catalyzed by H₃PO₄, of steam with ethylene derived from oil:
C₂H₄(g) + H₂O(g) ⇄ C₂H₅OH(g)
ΔH°rxn = -47.8kj Kc = 9 ×10³ at 600K(c) Calculate Kc at 450. K.