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Explain change in enthalpy related to reaction. |
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Answer» Solution :In a CHEMICAL reaction, reactants are converted into products and is represented by, Reactants `to` Products The enthalpy CHANGE accompanying a reaction is called the reaction enthalpy. The enthalpy change of a chemical reaction, is given by the symbol `Delta_(r) H`. `Delta_(r) H = ("Sum of enthalpies of products")-(" Sum of enthalpies of reactants" )` `=sum_(i) a_(i) H_("products") - sum_(i) b_(i) H_("reactants")` Here symbol `sum` is used for summation and `a_(i) and b_(i)` are the stoichiometric coefficients of the products and reactants respectively in the balanced chemical equation. For example, for the reaction `CH_(4(g)) + 2O_(2(g)) to CO_(2(g)) + 2H_(2) O_((L))` `Delta_(r) H = sum_(i) a_(i) H_("products") - sum_(i) b_(i) H_("reactants")` `= [H_(m) ( CO_(2), g) + 2H_(m) (H_(2) O , l)]- [H_(m) (CH_(4) , g) + 2H_(m) (O_(2) , g) ]` where, `H_(m)` is the MOLAR enthalpy |
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