Ch.7 - Thermochemistry

Tro - Chemistry: A Molecular Approach 6th Edition

Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217당신이 사용하는 게 아니라요?교과서 변경

Tro 6th Edition

Ch.7 - Thermochemistry

문제 77

7장, 문제 77

When 1.03 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 24.2 °C to 2931.4 °C. Find ΔErxn for the combustion of biphenyl in kJ>mol biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/°C.

검증된 단계별 안내

Identify the given values: mass of biphenyl = 1.03 g, initial temperature = 24.2 °C, final temperature = 2931.4 °C, and heat capacity of the calorimeter = 5.86 kJ/°C.

Calculate the temperature change (ΔT) by subtracting the initial temperature from the final temperature: ΔT = 2931.4 °C - 24.2 °C.

Use the formula q = C_calorimeter * ΔT to calculate the heat absorbed by the calorimeter, where q is the heat absorbed and C_calorimeter is the heat capacity of the calorimeter.

Convert the mass of biphenyl to moles using its molar mass (C12H10), which is approximately 154.21 g/mol.

Calculate ΔE_rxn in kJ/mol by dividing the heat absorbed by the calorimeter (q) by the number of moles of biphenyl.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

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

Combustion Reaction

A combustion reaction is a chemical process in which a substance reacts rapidly with oxygen, producing heat and light. In this case, biphenyl (C12H10) combusts, releasing energy as it transforms into carbon dioxide and water. Understanding the stoichiometry of the reaction is essential for calculating the energy change associated with the combustion.

Calorimetry

Calorimetry is the science of measuring the heat of chemical reactions or physical changes. In this scenario, a bomb calorimeter is used to measure the heat released during the combustion of biphenyl. The temperature change observed in the calorimeter, along with its heat capacity, allows for the calculation of the energy change (ΔErxn) for the reaction.

Enthalpy Change (ΔErxn)

The enthalpy change (ΔErxn) for a reaction represents the amount of energy absorbed or released during the reaction per mole of reactant. It is calculated using the formula ΔErxn = -C × ΔT, where C is the heat capacity of the calorimeter and ΔT is the change in temperature. This value is crucial for understanding the energy dynamics of the combustion process.

관련 실천

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교과서 질문

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For each generic reaction, determine the value of ΔH₂ in terms of ΔH₁.

a. A + B → 2 C ΔH₁

2 C→ A + B ΔH₂ = ?

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