Enthalpy changes calculation

The decomposition reactions of Ca(N()2)2 are similar to those for the Ba and Sr salts. Centnerszwer and Piekelny13 measured the decomposition pressure over the temperature range 540 to 588 K. In an inert atmosphere log P is linear in 1/T p varied from 0 at 540 K to 693 torr at 588 K. This suggests that a single reaction is responsible for the measured pressure, but it is not at all clear what this reaction is, since the enthalpy change calculated by the authors from the pressure data (147.7 kJ) differs considerably from AH° at 298 K for the reaction cited by the authors. 

Compare your answers from parts a and b of Exercise 31 with AH values calculated for each reaction using standard enthalpies of formation in Appendix 4. Do enthalpy changes calculated from bond energies give a reasonable estimate of the actual values ... 

The three equations shown add up to the same overall reaction as equations 1 and 2 in Example 5.3. Thus, the total enthalpy change, —47 kcal/mol is the same as the total enthalpy change calculated in Example 5.3. Why then do these equations not represent a mechanism for... 

The enthalpy change calculated above is the enthalpy change if 1 mole of CO2 is produced. The problem asks for the enthalpy change if 66.8 g of CO2 are produced. We need to use the molar mass of CO2 as a conversion factor. 

Applying Hess s law Given a set of reactions with enthalpy changes, calculate AH for a reaction obtained from these other reactions by using Hess s law. (EXAMPLE 6.7)... 

Because bond enthalpies are often average values it means that enthalpy changes calculated using bond enthalpies will not be exactly equal to an accurate experimentally determined value. 

When the law is used to an electrode reaction with the given electron transfer number at the given temperature, the enthalpy change calculated based on the electric work done and the heat effect obtained experimentally differs from that calculated by Eq.(30) on the current thermodynamic databank including the ion data. The difference between them is almost a constant. For this phenomenon it has been not yet explained reasonably so far, and this greatly influenced the development of thermoelectrochemistiy. 

Given the heat of reaction enthalpy change), calculate the loss or gain of heat for an exothermic or endothermic reaction. 

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