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Ch.5 - Thermochemistry
Brown - Chemistry: The Central Science 15th Edition
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Tutti i libri di testoBrown 15th EditionCh.5 - ThermochemistryProblema 39b
Capitolo 5, Problema 39b

The complete combustion of ethanol, C2H5OH(l), to form H2O(g) and CO2(g) at constant pressure releases 1235 kJ of heat per mole of C2H5OH. b. Draw an enthalpy diagram for the reaction.

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Draw a horizontal line to represent the enthalpy level of the reactants, C_2H_5OH(l) and O_2(g).
Draw another horizontal line below the reactants' line to represent the enthalpy level of the products, H_2O(g) and CO_2(g).
Label the reactants' line with 'Reactants: C_2H_5OH(l) + O_2(g)' and the products' line with 'Products: H_2O(g) + CO_2(g)'.
Draw a vertical arrow pointing downward from the reactants' line to the products' line to indicate the release of energy.
Label the arrow with '-1235 kJ/mol' to indicate the exothermic nature of the reaction, as energy is released.

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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, C2H5OH, its combustion results in the formation of carbon dioxide (CO2) and water (H2O), releasing energy. Understanding this reaction is crucial for analyzing energy changes and the products formed during combustion.
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Combustion Apparatus

Enthalpy Change

Enthalpy change (ΔH) refers to the heat content change of a system at constant pressure during a chemical reaction. For the combustion of ethanol, the enthalpy change is negative, indicating that the reaction is exothermic, as it releases 1235 kJ of heat per mole. This concept is essential for interpreting energy diagrams and understanding the thermodynamics of the reaction.
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Enthalpy of Formation

Enthalpy Diagram

An enthalpy diagram visually represents the energy changes during a chemical reaction. It typically shows the enthalpy of reactants and products, along with the enthalpy change (ΔH). For the combustion of ethanol, the diagram would illustrate the decrease in enthalpy as the reactants convert to products, highlighting the energy released in the process.
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Enthalpy of Formation
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