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(Solved): 2. For the following chemical equation: 3C(s)+4H2(g)C3H8(g) a. Using Table 1, what ...
2. For the following chemical equation: a. Using Table 1, what is the standard enthalpy change of formation for ? b. The standard enthalpy change for this reaction can also be found using Hess's Law. Find the standard enthalpy change of reaction using Hess's Law and the following chemical equations c. Calculate the percent error using the enthalpy change of formation as the theoretical value.
Expert Answer
In part (a), we are given the standard enthalpy change of formation for directly from Table 1, which is -104 kJ/mol. This value represents the enthalpy change when one mole of is formed from its constituent elements in their standard states at a pressure of 1 bar and a temperature of 298 K.In part (b), we use Hess's Law to calculate the standard enthalpy change of reaction, which is the enthalpy change for the reaction as written in the given chemical equation. Hess's Law states that the enthalpy change of a reaction is equal to the sum of the enthalpy changes of any series of reactions that can be added together to give the overall reaction.2 H2(g) + O2(g) ? 2 H2O(g) ?H = -2(-393.5 kJ/mol) = +787 kJ/molNext, we need to multiply the first equation by 5/4 to make the number of moles of O2(g) equal on both sides:5/4 C3H8(g) + 5 O2(g) ? 15/4 CO2(g) + 5 H2O(g) ?H = 5(-2043 kJ/mol)/4 = -510.75 kJ/molNow we can add the two equations together and cancel out the common species (H2O(g)) to get the overall equation:3 C(s) + 4 H2(g) ? C3H8(g) ?H = -483.6 kJ/mol