Ch.9 - Chemical Bonding I: The Lewis Model

Tro - Chemistry: A Molecular Approach 4th Edition

Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831당신이 사용하는 게 아니라요?교과서 변경

Tro 4th Edition

Ch.9 - Chemical Bonding I: The Lewis Model

문제 82

9장, 문제 82

Ethanol is a possible fuel. Use average bond energies to calculate ΔHrxn for the combustion of ethanol. CH₃CH₂OH(g) + 3 O2(g) → 2 CO₂(g) + 3 H₂O(g)

검증된 단계별 안내

Step 1: Write the balanced chemical equation for the combustion of ethanol.

Step 2: Identify and list all the bonds broken in the reactants. For ethanol (CH3CH2OH), consider C-H, C-C, C-O, and O-H bonds. For O2, consider the O=O bond.

Step 3: Identify and list all the bonds formed in the products. For CO2, consider C=O bonds. For H2O, consider O-H bonds.

Step 4: Use the average bond energies to calculate the total energy required to break the bonds in the reactants.

Step 5: Use the average bond energies to calculate the total energy released when forming the bonds in the products. Then, calculate \( \Delta H_{\text{rxn}} \) by subtracting the total energy of bonds formed from the total energy of bonds broken.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Bond Energies

Bond energies refer to the amount of energy required to break a bond between two atoms in a molecule. In the context of chemical reactions, the total energy required to break bonds in the reactants must be compared to the energy released when new bonds are formed in the products. This concept is crucial for calculating the enthalpy change (ΔHrxn) of a reaction.

Enthalpy Change (ΔHrxn)

Enthalpy change (ΔHrxn) is the heat change associated with a chemical reaction at constant pressure. It can be calculated using the formula ΔHrxn = Σ(Bond Energies of Reactants) - Σ(Bond Energies of Products). A negative ΔHrxn indicates that the reaction is exothermic, meaning it releases heat, which is typical for combustion reactions like that of ethanol.

Combustion Reaction

A combustion reaction is a chemical process in which a substance reacts rapidly with oxygen, producing heat and light. In the case of ethanol, the reaction with oxygen produces carbon dioxide and water. Understanding the stoichiometry of the reaction and the products formed is essential for accurately calculating the enthalpy change and assessing the energy output of the fuel.

관련 실천

교과서 질문

Order these compounds in order of decreasing carbon–carbon bond length: HCCH, H₂CCH₂, H₃CCH₃.

In the Chemistry and the Environment box on free radicals in this chapter, we discussed the importance of the hydroxyl radical in reacting with and eliminating many atmospheric pollutants. However, the hydroxyl radical does not clean up everything. For example, chlorofluorocarbons—which destroy stratospheric ozone—are not attacked by the hydroxyl radical. Consider the hypothetical reaction by which the hydroxyl radical might react with a chlorofluorocarbon: OH(g) + CF₂Cl₂(g) → HOF(g) + CFCl₂(g) Use bond energies to explain why this reaction is improbable. (The C–F bond energy is 552 kJ/mol.)

734

views

교과서 질문

Hydrogenation reactions are used to add hydrogen across double bonds in hydrocarbons and other organic compounds. Use average bond energies to calculate ΔH_rxn for the hydrogenation reaction. H₂C=CH₂(g) + H₂(g) → H₃C–CH₃(g)

Which of the two compounds, H₂NNH₂ and HNNH, has the strongest nitrogen-nitrogen bond, and which has the shorter nitrogen-nitrogen bond.

1937

views

Ethanol is a possible fuel. Use average bond energies to calculate ΔHrxn for the combustion of ethanol. CH3CH2OH(g) + 3 O2(g) → 2 CO2(g) + 3 H2O(g)

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Bond Energies

Enthalpy Change (ΔHrxn)

Combustion Reaction

Ethanol is a possible fuel. Use average bond energies to calculate ΔHrxn for the combustion of ethanol. CH₃CH₂OH(g) + 3 O2(g) → 2 CO₂(g) + 3 H₂O(g)