The complete combustion of ethanol, C 2 H 5 OH(l), to form H 2 O(g) and CO 2 (g) at constant pressure releases 1235 kJ of heat per mole of C 2 H 5 OH. b. Draw an enthalpy diagram for the reaction.

hi everyone. This problem reads at constant pressure. The following reaction releases 1255.8 kg jewels of energy provide the correct entropy diagram for the reaction. Okay, so we want to draw a entropy dia program which is also referred to as a reaction profile. And for a reaction profile it shows the progress of a chemical reaction as a function of potential energy. All right. So, we're going to do our reaction profile here and we're going to have our reaction progress. Okay. And potential energy. All right. And our reaction progress is in time. Alright, so here we notice that our reaction is releasing energy and what that means is our change in entropy is negative. 1,255.8 kila jules. Okay, So for an exotic thermic reaction profile, the potential energy of the products is lower than the reactant. Alright, so with our reaction profile we have our reactant since and then we have our transition state and then we have our products. Okay, so we're right here reactant since and products. All right. Now this space here, this space here is our activation energy and this space here is our change and entropy and our product our initial energy Excuse me, are potential energy of the product is lower than the reactant and this gives us that negative value. Okay, and so this is going to be the correct entropy diagram for this reaction. That's it for this problem. I hope this is helpful

Ch.5 - Thermochemistry

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Brown 15th Edition

Ch.5 - Thermochemistry

Problem 39b

Chapter 5, Problem 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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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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.

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.

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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Without referring to tables, predict which of the following has the higher enthalpy in each case: (a) 1 mol CO₂(s) or 1 mol CO₂(g) at the same temperature

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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Key Concepts

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Enthalpy Diagram

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.