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Ch.5 - Thermochemistry
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Brown 14th EditionCh.5 - Thermochemistry문제 44c
5장, 문제 44c

Consider the following reaction: 2 CH3OH(g) → 2 CH4(g) + O2(g) ΔH = +252.8 kJ (c) For a given sample of CH3OH, the enthalpy change during the reaction is 82.1 kJ. How many grams of methane gas are produced?

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Identify the stoichiometry of the reaction: 2 moles of CH3OH produce 2 moles of CH4 and 1 mole of O2. The enthalpy change (ΔH) for this reaction is +252.8 kJ for 2 moles of CH3OH.
Determine the enthalpy change per mole of CH3OH by dividing the given ΔH by 2, since the reaction involves 2 moles of CH3OH. This will give you the enthalpy change for 1 mole of CH3OH.
Calculate the number of moles of CH3OH that correspond to the given enthalpy change of 82.1 kJ. Use the formula: \( \text{moles of CH3OH} = \frac{\text{given enthalpy change}}{\text{enthalpy change per mole of CH3OH}} \).
Since the stoichiometry of the reaction shows that 2 moles of CH3OH produce 2 moles of CH4, the moles of CH4 produced will be equal to the moles of CH3OH reacted.
Convert the moles of CH4 to grams using the molar mass of CH4 (16.04 g/mol). Use the formula: \( \text{mass of CH4} = \text{moles of CH4} \times \text{molar mass of CH4} \).

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주요 개념

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

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced equation. It allows us to determine the relationships between the amounts of substances involved. In this case, the stoichiometric coefficients indicate that 2 moles of CH3OH produce 2 moles of CH4, establishing a 1:1 ratio for their quantities.
추천 영상:
가이드 코스
01:16
Stoichiometry Concept

Enthalpy Change (ΔH)

Enthalpy change (ΔH) represents the heat absorbed or released during a chemical reaction at constant pressure. A positive ΔH indicates an endothermic reaction, meaning energy is absorbed. In this reaction, the given ΔH of +252.8 kJ signifies that 2 moles of CH3OH absorb this amount of energy to produce the products.
추천 영상:
가이드 코스
02:34
Enthalpy of Formation

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between moles and grams. For methane (CH4), the molar mass is approximately 16.04 g/mol, which will be used to calculate the mass of methane produced based on the moles derived from the enthalpy change.
추천 영상:
가이드 코스
02:11
Molar Mass Concept
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