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Ch.19 - Chemical Thermodynamics
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoBrown 14th EditionCh.19 - Chemical ThermodynamicsProblema 74a
Capitolo 19, Problema 74a

The fuel in high-efficiency natural-gas vehicles consists primarily of methane (CH4). (a) How much heat is produced in burning 1 mol of CH4(g) under standard conditions if reactants and products are brought to 298 K and H2O(l) is formed?

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Identify the chemical reaction for the combustion of methane: CH_4(g) + 2O_2(g) \(\rightarrow\) CO_2(g) + 2H_2O(l).
Determine the standard enthalpy change (\( \Delta H^\circ \)) for the reaction using standard enthalpies of formation: \( \Delta H^\circ = \sum \Delta H^\circ_f(\text{products}) - \sum \Delta H^\circ_f(\text{reactants}) \).
Look up the standard enthalpies of formation for each substance involved: CH_4(g), O_2(g), CO_2(g), and H_2O(l).
Substitute the values into the enthalpy change equation: \( \Delta H^\circ = [\Delta H^\circ_f(\text{CO}_2(g)) + 2 \times \Delta H^\circ_f(\text{H}_2O(l))] - [\Delta H^\circ_f(\text{CH}_4(g)) + 2 \times \Delta H^\circ_f(\text{O}_2(g))] \).
Calculate the \( \Delta H^\circ \) for the reaction to find the heat produced when 1 mol of CH_4 is burned.

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Combustion Reaction

A combustion reaction is a chemical process in which a substance (typically a hydrocarbon) reacts with oxygen to produce heat, carbon dioxide, and water. In the case of methane (CH4), the reaction releases energy as it converts the reactants into products, making it a key process in energy production for fuels.
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Combustion Apparatus

Enthalpy of Combustion

The enthalpy of combustion is the amount of heat released when one mole of a substance is completely burned in oxygen under standard conditions. For methane, this value is crucial for determining the energy output of natural gas vehicles and is typically expressed in kilojoules per mole (kJ/mol).
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Combustion Apparatus

Standard Conditions

Standard conditions refer to a set of specific conditions used as a reference point in thermodynamics, typically defined as 1 atmosphere of pressure and a temperature of 298 K (25°C). These conditions are important for calculating thermodynamic properties, such as enthalpy changes, ensuring consistency in measurements and comparisons.
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Standard Reduction Potentials
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Domanda del libro di testo

(a) Using data in Appendix C, estimate the temperature at which the free-energy change for the transformation from I2(s) to I2(g) is zero. (b) Use a reference source, such as Web Elements (www.webelements.com), to find the experimental melting and boiling points of I2. (c) Which of the values in part (b) is closer to the value you obtained in part (a)?

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Domanda del libro di testo

The fuel in high-efficiency natural-gas vehicles consists primarily of methane (CH4). (b) What is the maximum amount of useful work that can be accomplished under standard conditions by this system?

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