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GivenC_(("graphite"))+O_(2)(g)rarrCO_(2)(g), ""Delta_(r)H^(@)=-393.5 kJ mol^(-1),H_(2)(g)+(1)/(2)O_(2)(g)rarrH_(2)O(l),""Delta_(r)H^(@)=-285.8 kJ mol^(-1),CO_(2)(g)+2H_(2)O(l)rarrCH_(4)(g)+2O_(2)(g),Delta_(r)H^(@)=-890.3 kJ mol^(1),Based on the above thermochemical equations, the value of Delta_(r)H^(@) at 298 K for the reaction C_(("graphite"))+2H_(2)(g)rarrCH_(4)(g) will be |
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Answer» `+144.0 kJ mol^(1)` `DeltaH_(r)=-393.5kJ//mol=DeltaH_(r)CO_(2)(g)` `H_(2)(g)+(1)/(2)O_(2)(g)rarrH_(2)O(l)` `DeltaH_(r)=-285.8 kJ//mol=DeltaH_(F)H_(2)O(l)` `CO_(2)(g)+2H_(2)O(l)rarrCH_(4)(g)+2O_(2)(g)` `DeltaH_(r)=DeltaH_(f)(CH_(4))-DeltaH_(f)CO_(2)(f)-2DeltaH_(f)H_(2)O(l)=890.3` `IMPLIES DeltaH_(f)CH_(4)+393.5+2xx285.8=890.3` `impliesDeltaH_(f)CH_(4)(g)=-74.8 kJ//mol` |
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