How do you calculate enthalpy change in a chemical reaction?

Sample interview questions: How do you calculate enthalpy change in a chemical reaction?

Sample answer:

1. Define the System and Reaction of Interest:

2. Clearly identify the system undergoing the chemical reaction and define the reaction of interest.

3. Determine the Initial and Final States:

4. Specify the initial state (reactants) and the final state (products) of the reaction.

5. Calculate the Enthalpy Change:

6. ΔH = H(products) – H(reactants)
   • H(products): Enthalpy of the products in their final state
   • H(reactants): Enthalpy of the reactants in their initial state

Methods for Calculating Enthalpy Change:

1. Direct Calorimetry:
2. Use a calorimeter to measure the heat released or absorbed during the reaction.

3. ΔH = -Q, where Q is the heat flow.

4. Indirect Calorimetry:

5. Use thermochemical data, such as heats of formation, to calculate ΔH.

6. ΔH = ΣH(products) – ΣH(reactants)

7. Hess’s Law:

8. Use enthalpy data from other reactions to calculate ΔH for the reaction of interest.

9. ΔH = ΣΔH(sub-reactions)

10. Bond Enthalpies:

11. Estimate ΔH based on the bond enthalpies of the reactants and products.

12. ΔH = ΣH(bonds broken) – ΣH(bonds formed)

13. Quantum Mechanical Calculations:

14. Use computational meth… Read full answer

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