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Combustion enthalpy of carbon is .-x. kJ, Enthalpy of formation of water is .-y. kJ and combustion enthalpy of methane is .-z. kJ calculate the enthalpy of formation of methane. |
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Answer» `(-x-y+z)` kJ (i) `C_((s)) + O_(2(g)) = CO_(2(g)) , DELTA H_((i)) = -x` kJ Enthalpy of formation of WATER : (ii) `H_(2(g)) + (1)/(2) O_(2(g)) = H_(2) O_((l)) , Delta H_(ii) =-y "kJ"` Combustion enthalpy of methane : (iii) `CH_(4(g)) + 2O_(2(g)) = CO_(2(g)) + 2H_(2) O_((l)) DeltaH_((iii)) =z "kJ"` Enthalpy of formation of methane : (iv) `C_((s)) + 2H_(2(g)) = CH_(4(g)), Delta H_((iv)) = ?` According to Hess. rule : (equation) (i)) + (2 · equation (ii)) - (equation (iii)) = equation (iv) eq. (i) : `C_((s)) + O_(2(g)) = CO_(2(g)), DeltaH_((i)) =-x "kJ"` eq. (ii) `:2H_(2(g)) + O_(2(g)) = 2H_(2) O_((l)) , DeltaH_((ii)) = -2y "kJ"` eq. (iii) : `[-CH_(4(g)) + 2O_(2(g)) = CO_(2(g)) + 2H_(2) O_((l)),DeltaH_((iii)) = -z "kJ"`] eq. (iv) : `C_((s)) + 2H_(2(g)) to CH_(4(g)) , DeltaH_((iv)) = DeltaH_((iv)) = (-x-2y+z)` kJ |
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