1. Chemistry
2. Physical Chemistry
3. Energetics and Thermodynamics
4. Hess’ Law
5. 298069

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Several reactions and their standard reaction enthalpies at 298.15k are given:

CaC2(s) + 2H2O(l)--> (CaOH)2(s) + C2H2 (g)
deltaH:-127.9kj/mol

Ca(s) + 1/2 O2(g)--> CaO(s)
deltaH: -635.1

CaO(s) + H2O (l)--> Ca(OH)2 (s)
deltaH: -65.2

The standard enthalpies of combustion of graphite and C2H2(g) are -393.51 and -1299.58 kj/mol, respectively. Calculate the standard enthalpy of formation of CaC2 (s) at 25° C.