Calcium carbide (CaC2) reacts with water to form acetylene (C2H2) and Ca(OH)2. From the following enthalpy of reaction data, calculate Δf for CaC2(s):
CaC2(s) = 2H20(l) --> Ca(OH)2(s) + C2H2(g) ΔH = -127.2 kJ
H20(l) -285.3 kJ/mol
C2H2(g) 226.77 kJ/mol
Ca(OH)2(s) -986.2 kJ/mol