For the chemical reaction Ca (s) + ½ O2 (g) → CaO (s) AH° = -635 kJ/mol. %3D What is the enthalpy for the reaction 2 CaO (s) → 2 Ca (s) + O2 (g)? kJ/mol 1 2 4 C 7 8 9. +/- х 100
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.
![### Chemical Reaction and Enthalpy Calculation
For the chemical reaction:
\[ \text{Ca (s) + ½ O}_2 \text{ (g) } \rightarrow \text{CaO (s)} \]
the standard enthalpy change, \( \Delta H^\circ \), is \(-635 \text{ kJ/mol}\).
#### Question
What is the enthalpy for the reaction:
\[ \text{2 CaO (s)} \rightarrow \text{2 Ca (s) + O}_2 \text{ (g)}? \]
#### Explanation
**Reaction Analysis:**
- The given reaction is the formation of calcium oxide (CaO) from calcium (Ca) and oxygen (\(\text{O}_2\)).
- The enthalpy change of this formation reaction is exothermic with \(-635 \text{ kJ/mol}\).
**Calculating the Enthalpy for the Reverse Reaction:**
- The reaction we are asked to analyze is the reverse of the given formation reaction.
- For reversible reactions, the enthalpy change has the same magnitude but opposite sign.
**Result:**
For the reaction \( \text{2 CaO (s)} \rightarrow \text{2 Ca (s) + O}_2 \text{ (g)}\):
- The enthalpy change will be \( \Delta H = +635 \text{ kJ/mol} \times 2 = +1270 \text{ kJ/mol}\).
#### Diagram Description
The image includes a calculator-like interface for inputting numerical values. There are buttons labeled with numbers (0-9), a decimal point, a sign change button (\(+/-\)), a delete button (×), and a clear button (C). There is also a function for multiplying by 10. This section allows for the entering and manipulation of values for the calculation of enthalpy.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe6cad9fc-aa22-494d-997b-d7e31e29d4fe%2F64565f03-3cee-4724-be1d-bbf6ddbb900e%2Frdfs44_processed.png&w=3840&q=75)
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