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Ch.9 - Thermochemistry: Chemical Energy
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145당신이 사용하는 게 아니라요?교과서 변경
모든 교과서McMurry 8th EditionCh.9 - Thermochemistry: Chemical Energy문제 106
9장, 문제 106

The standard enthalpy change for the reaciton of SO3(g) with H2O(l) to yield H2SO4(aq) is ΔH° = -227.8 kJ. Use the information in Problem 9.104 to calculate ΔH°f for H2SO4(aq) in kJ/mol. [For H2O(l), ΔH°f = -285.88 kJ/mol.]

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1
Identify the given reaction: \( \text{SO}_3(g) + \text{H}_2\text{O}(l) \rightarrow \text{H}_2\text{SO}_4(aq) \).
Recognize that the standard enthalpy change for the reaction, \( \Delta H^\circ \), is given as -227.8 kJ.
Recall that the standard enthalpy of formation, \( \Delta H^\circ_f \), for a compound is the enthalpy change when one mole of the compound is formed from its elements in their standard states.
Use the formula for the enthalpy change of a reaction: \( \Delta H^\circ = \sum \Delta H^\circ_f(\text{products}) - \sum \Delta H^\circ_f(\text{reactants}) \).
Substitute the known values into the equation: \( -227.8 = \Delta H^\circ_f(\text{H}_2\text{SO}_4(aq)) - [\Delta H^\circ_f(\text{SO}_3(g)) + (-285.88)] \), and solve for \( \Delta H^\circ_f(\text{H}_2\text{SO}_4(aq)) \).

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주요 개념

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

Enthalpy Change (ΔH)

Enthalpy change (ΔH) is a measure of the heat absorbed or released during a chemical reaction at constant pressure. A negative ΔH indicates that the reaction is exothermic, meaning it releases heat. Understanding ΔH is crucial for calculating the standard enthalpy of formation (ΔH°f) of compounds, as it reflects the energy changes associated with forming products from reactants.
추천 영상:
가이드 코스
02:34
Enthalpy of Formation

Standard Enthalpy of Formation (ΔH°f)

The standard enthalpy of formation (ΔH°f) is the change in enthalpy when one mole of a compound is formed from its elements in their standard states. It is a key value used in thermodynamic calculations to determine the energy changes in reactions. Knowing the ΔH°f values of reactants and products allows for the calculation of the overall enthalpy change for a reaction.
추천 영상:
가이드 코스
02:34
Enthalpy of Formation

Hess's Law

Hess's Law states that the total enthalpy change for a reaction is the sum of the enthalpy changes for individual steps, regardless of the pathway taken. This principle allows for the calculation of ΔH°f for compounds by using known ΔH values from related reactions. It is particularly useful when direct measurement of ΔH°f is not possible, enabling the use of other thermodynamic data to find the desired value.
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가이드 코스
02:03
Hess's Law
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