已知:(1)Zn(s)+1/2O2(g)=ZnO(s);ΔH=-348.3kJ/mol(2)2Ag(s)+1/2 O2(g)= Ag2O(s);ΔH= -31.0kJ/mol
则Zn(s)+ Ag2O(s)= ZnO(s)+ 2Ag(s)的ΔH等于