Consider the balanced reaction 4 A+5 B →3 C+4 D and the enthalpies of formation provided in the table below. AHf Compound (kJ/mol) A 56.4 -399.9 60.7 -273.4 Calculate the AH value for the overall reaction in kJ per mole of reaction. Report your answer to one decimal place (ignore significant figures).
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.
![**Calculating the Enthalpy Change of a Reaction**
Consider the balanced reaction:
\[ 4 \text{A} + 5 \text{B} \rightarrow 3 \text{C} + 4 \text{D} \]
The enthalpies of formation (\(\Delta H_f\)) for the compounds involved in the reaction are provided in the table below:
| Compound | \(\Delta H_f\) (kJ/mol) |
|----------|--------------------------|
| A | 56.4 |
| B | -399.9 |
| C | 60.7 |
| D | -273.4 |
**Task:** Calculate the \(\Delta H\) value for the overall reaction in kJ per mole of reaction.
**Instructions:** Report your answer to one decimal place (ignore significant figures).
The enthalpy change (\(\Delta H\)) for the reaction can be calculated using the formula:
\[ \Delta H_{reaction} = \sum \Delta H_f (\text{products}) - \sum \Delta H_f (\text{reactants}) \]
Where:
- \(\sum \Delta H_f (\text{products})\) is the sum of the enthalpies of formation of the products, each multiplied by their respective coefficients from the balanced equation.
- \(\sum \Delta H_f (\text{reactants})\) is the sum of the enthalpies of formation of the reactants, each multiplied by their respective coefficients from the balanced equation.
**Step-by-Step Calculation:**
1. **Calculate the total \(\Delta H_f\) for the products:**
- \(3 \times \Delta H_f(\text{C}) = 3 \times 60.7 \, \text{kJ/mol} = 182.1 \, \text{kJ/mol}\)
- \(4 \times \Delta H_f(\text{D}) = 4 \times (-273.4) \, \text{kJ/mol} = -1093.6 \, \text{kJ/mol}\)
- Total \(\Delta H_f\) for products = \(182.1 \, \text{kJ/mol} + (-1093.6 \, \text{kJ/mol}) = -911.5 \, \text{kJ/mol}\)
2. **Calculate the total \(\Delta](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fac5cb3b0-7591-4200-b69b-d41956f36b92%2F1dc82b73-279e-41f6-a11f-bff6278571c3%2F7cz0vve_processed.jpeg&w=3840&q=75)
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