5. Given the following data calculate AH for the reaction: NO (g) + 0 (g) → NO2 (g) Data 202(g) → 302(g) 02(g) → 20(g) NO (g) + 03(g) → NO2(g) + 02(g) AH = -427 kJ AH = +495 kJ AH = -199 kJ
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.
![Given the following data, calculate ΔH for the reaction:
\[ NO(g) + O(g) \rightarrow NO_2(g) \]
**Data:**
1. \[ 2O_2(g) \rightarrow 3O_2(g) \]
- ΔH = -427 kJ
2. \[ O_2(g) \rightarrow 2O(g) \]
- ΔH = +495 kJ
3. \[ NO(g) + O_3(g) \rightarrow NO_2(g) + O_2(g) \]
- ΔH = -199 kJ
This information can be used to calculate the enthalpy change, ΔH, for the given reaction using Hess's Law.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbfeb1fc9-1e53-4773-bcdd-6ab5fbea65c1%2F0993f951-882a-4b2f-a029-04fa49578ac9%2Fl4i89c5_processed.png&w=3840&q=75)
Heat of reaction is defined as difference of energy of product and energy of Reactant.
If heat of reaction is negative then process is exothermic or Heat is releasing and if heat of reaction is positive then process is endothermic or Heat is absorbing.
If we reverse any reaction then magnitude of the ∆H of new reaction will be same but sign will be opposite.
If we multiply by any number to the reaction then ∆H should be also multiply by same number.
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