5. Reaction Enthalpy. balance and calculate AHxn for the following chemical equations. AH (kJ/mol): HCN= 130.5, Ca3(PO4)2=-4120.8, H3PO4--1288, SiCl₁=-640.1, SiO2= -910.9, Mg0=-601.6, HCl--167.16 a) NH3(g) + O₂(g) + CH4(g) HCN(g) + H₂O(g)
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.


Note - Since the given question is a multiple question, hence I solved first question according to rules of bartleby. Please repost the rest question separately.
Here we have to determine standard enthalpy change of the following given reaction from the following given data
The standard enthalpy formation of NH3 , CH4, HCN and H2O are -46.1 Kj/mol, -74Kj/mol, 130Kj/mol and -241.82 Kj respectively. Standard enthalpy formation of Stable elements are zero Kj.
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