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Questions and Answers
Which of the following statements correctly describes the energy changes associated with bond formation and bond breaking in a chemical reaction?
Which of the following statements correctly describes the energy changes associated with bond formation and bond breaking in a chemical reaction?
- Breaking bonds releases energy (exothermic), while forming bonds requires energy (endothermic).
- Both breaking and forming bonds require energy (endothermic).
- Both breaking and forming bonds release energy (exothermic).
- Breaking bonds requires energy (endothermic), while forming bonds releases energy (exothermic). (correct)
For the combustion of methane (CH₄), what is the significance of comparing the total energy required to break the bonds in the reactants to the total energy released in the formation of bonds in the products?
For the combustion of methane (CH₄), what is the significance of comparing the total energy required to break the bonds in the reactants to the total energy released in the formation of bonds in the products?
- It determines whether the reaction is exothermic (releases energy) or endothermic (absorbs energy). (correct)
- It determines the rate of the reaction.
- It determines only if the reaction is spontaneous or non-spontaneous, not the energy change.
- It determines the equilibrium constant of the reaction.
Given the bond enthalpies: C-H (414 KJ/mole), O=O (498 KJ/mole), C=O (804 KJ/mole), and O-H (463 KJ/mole), and the balanced equation for methane combustion, what calculation determines the overall enthalpy change (ΔH) for the reaction?
Given the bond enthalpies: C-H (414 KJ/mole), O=O (498 KJ/mole), C=O (804 KJ/mole), and O-H (463 KJ/mole), and the balanced equation for methane combustion, what calculation determines the overall enthalpy change (ΔH) for the reaction?
- ΔH = [4(414) + 2(498)] - [2(804) + 4(463)]
- ΔH = [4(414) - 2(498)] - [2(804) - 4(463)]
- ΔH = [2(804) + 4(463)] - [4(414) + 2(498)] (correct)
- ΔH = [4(414) + 2(498)] + [2(804) + 4(463)]
How does the electronegativity difference between atoms in a bond relate to the bond's enthalpy?
How does the electronegativity difference between atoms in a bond relate to the bond's enthalpy?
Why might a reaction with stronger bonds in the reactants proceed at a slower rate?
Why might a reaction with stronger bonds in the reactants proceed at a slower rate?
According to Hess's Law, what factor determines the overall enthalpy change (ΔH) of a reaction?
According to Hess's Law, what factor determines the overall enthalpy change (ΔH) of a reaction?
In a multi-step reaction, how is the overall enthalpy change (ΔH) calculated, according to Hess's Law?
In a multi-step reaction, how is the overall enthalpy change (ΔH) calculated, according to Hess's Law?
For the reaction C(s) + O₂(g) → CO₂(g), which proceeds via the two steps C(s) + ½ O₂(g) → CO(g) and CO(g) + ½ O₂(g) → CO₂(g), with ΔH₁ = -111 KJ/mole and ΔH₂ = -283 KJ/mole respectively, is the overall reaction endothermic or exothermic, and what is the overall ΔH?
For the reaction C(s) + O₂(g) → CO₂(g), which proceeds via the two steps C(s) + ½ O₂(g) → CO(g) and CO(g) + ½ O₂(g) → CO₂(g), with ΔH₁ = -111 KJ/mole and ΔH₂ = -283 KJ/mole respectively, is the overall reaction endothermic or exothermic, and what is the overall ΔH?
Using tabulated bond enthalpy data and Hess's Law, scientists can determine the (\Delta)H for reactions. What is a primary reason for using these methods instead of direct measurement?
Using tabulated bond enthalpy data and Hess's Law, scientists can determine the (\Delta)H for reactions. What is a primary reason for using these methods instead of direct measurement?
How does the magnitude of bond enthalpy relate to the strength of a chemical bond, and what implication does this have for chemical reactions?
How does the magnitude of bond enthalpy relate to the strength of a chemical bond, and what implication does this have for chemical reactions?
Flashcards
Conservation of Energy
Conservation of Energy
Energy is neither created nor destroyed, but transformed.
Bond Energy Changes
Bond Energy Changes
Breaking bonds requires energy, an endothermic process; forming bonds releases energy, an exothermic process.
Exothermic Reaction
Exothermic Reaction
Reactions that release excess energy, indicated by ΔH < 0.
Endothermic Reaction
Endothermic Reaction
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Polar Bonds
Polar Bonds
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Hess's Law
Hess's Law
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Hess's Law application
Hess's Law application
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Enthalpy Change
Enthalpy Change
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Calculating ΔH
Calculating ΔH
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Study Notes
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