Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

8. Thermochemistry

Enthalpy of Formation

General Chemistry

8. Thermochemistry

Enthalpy of Formation

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Multiple Choice

Use standard enthalpies of formation to calculate ΔH°_rxn for the following reaction: CaO(s) + CO2(g) → CaCO3(s). Which of the following is the correct ΔH°_rxn value?

-178.3 kJ/mol

-120.0 kJ/mol

120.0 kJ/mol

178.3 kJ/mol

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Verified step by step guidance

Identify the standard enthalpies of formation (ΔH°_f) for each compound involved in the reaction. These values are typically found in tables in chemistry textbooks or reliable online resources. For this reaction, you need the ΔH°_f for CaO(s), CO2(g), and CaCO3(s).

Write the balanced chemical equation for the reaction: CaO(s) + CO2(g) → CaCO3(s). Ensure that the equation is balanced with respect to all elements involved.

Apply the formula for calculating the standard enthalpy change of the reaction (ΔH°_rxn): ΔH°_rxn = ΣΔH°_f(products) - ΣΔH°_f(reactants). This formula involves subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products.

Substitute the standard enthalpies of formation values into the formula. For this reaction, it would be: ΔH°_rxn = ΔH°_f[CaCO3(s)] - (ΔH°_f[CaO(s)] + ΔH°_f[CO2(g)]).

Perform the arithmetic operation to find the ΔH°_rxn value. This will involve adding and subtracting the enthalpy values as per the formula. The result will give you the standard enthalpy change for the reaction.