To understand how standard enthalpy of reaction is related to the standard heats

Question

To understand how standard enthalpy of reaction is related to the standard heats of of the reactants and products. The standard enthalpy of reaction is the enthalpy change that occurs in a reaction when all the reactants and products are in their standard states The symbol for the standard enthalpy of is delta H where the subscript stands for "reaction." The standard enthalpy of a reaction is calculated from the standard heats of formation (delta H) (subscript for formation) of its reactants and products. Therefore, the standard enthalpy delta H of my reaction can be mathematically determined long as the standard heats of formation (delta H) of its reactants and products are known. In a chemical reaction involving reactants A and B and products C and D. aA + bB + cC + dD, the standard enthalpy delta H of the reaction is given by delta H = c delta H^degree _f (C) + d delta H^degree _f (D) - a delta H^degree _f (A) - b delta H^degree _f (B) Notice that the coefficients, a b c, d are an important part of this equation This formula is often generalized as follows, where the first sum on the right-hand side of the equation is a sum over the products and the second sum is over the reactants: delta H^degree = sigma delta H^degree _f - where m and n represent the appropriate coefficients for each substance? What is delta H^degree for the following chemical reaction? CO(g) + NH_3(g) rightarrow HCN(g) + H_2O(g) You can use the following table of standard heats of formation (delta H) to calculate the enthalpy of the given reaction Express the standard enthalpy of reaction to three significant figures and include the appropriate units.

Explanation / Answer

The Enthalpy change for the reaction according to the above mentioned formula will be :

=[130.5 + (-241.8) ] - [ (-110.5) + (-45.90)]

Delta Ho rxn = +45.1 KJ

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