5. Reaction Enthalpy. and calculate AH for the following chemical equations. AH (kJ/mol): HCN = 130.5, Cas(PO4)2=-4120.8, H3PO4--1288, SiCl₁=-640.1, SiO₂= -910.9, Mg0=-601.6, HCl=-167.16 b) Ca,(PO₂)2(3) + H₂SO.(1) —— CaSO4(s) + H₂PO.(1)
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.
![**5. Reaction Enthalpy.**
Calculate ΔH° for the following chemical equations. ΔH° (kJ/mol): HCN = 130.5, Ca₃(PO₄)₂ = −4120.8, H₃PO₄ = −1288, SiCl₄ = −640.1, SiO₂ = −910.9, MgO = −601.6, HCl = −167.16
**b)** \[ \square \, \text{Ca}_3(\text{PO}_4)_2(s) + \square \, \text{H}_2\text{SO}_4(l) \rightarrow \square \, \text{CaSO}_4(s) + \square \, \text{H}_3\text{PO}_4(l) \]
**Diagram Explanation:**
This is a chemical equation representing the reaction between calcium phosphate \(\text{Ca}_3(\text{PO}_4)_2\) and sulfuric acid \(\text{H}_2\text{SO}_4\) to form calcium sulfate \(\text{CaSO}_4\) and phosphoric acid \(\text{H}_3\text{PO}_4\). The squares indicate that you need to balance the equation by determining the correct stoichiometric coefficients for each chemical species.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5dbedc34-c1dd-4e16-ba9c-319b01d1eecb%2F7fa23fe9-bc81-4515-8013-8155b98f2203%2F8zqr9if_processed.jpeg&w=3840&q=75)
Here we are required to find the Enthalpy change for the given double displacement reaction.
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