Calculate Enthalpy Change: C6H5OH, CO2, H2O

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Discussion Overview

The discussion revolves around calculating the change in enthalpy for the combustion reaction involving phenol (C6H5OH), carbon dioxide (CO2), and water (H2O) using enthalpies of formation. Participants explore the necessary steps and information required for the calculation, including the need for a balanced reaction equation.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses uncertainty about how to approach the problem and requests guidance.
  • Another participant notes that a change in enthalpy implies changing parameters and asks if there are initial or final temperatures or other relevant data.
  • A suggestion is made to start with the balanced reaction equation as a foundational step.
  • A mathematical expression for calculating enthalpy change is provided, emphasizing the importance of the balanced chemical equation.
  • It is pointed out that a reactant is missing from the problem statement, prompting participants to consider what C6H5OH would react with in a combustion reaction and the implications for heat of formation.
  • Participants are encouraged to recall the relationship between heat of reaction and heats of formation for products and reactants.

Areas of Agreement / Disagreement

There is no consensus yet, as participants are still exploring the necessary components for the calculation and identifying missing information.

Contextual Notes

Participants have not yet established the balanced reaction equation or identified the missing reactant, which are critical for proceeding with the enthalpy calculation.

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Homework Statement


determine the change in enthalpy for the following reaction from the enthalpies of formation for the reactants and products. (C6H5OH -165 kJ/mol, CO2 -393.15 kJ/mol, H2O -285.83 kJ/mol)


Homework Equations





The Attempt at a Solution


No idea, been a while since I did this...if ever

Any direction is appreciated.
 
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A change in enthalpy would indicate that there were parameters in the question that were changing. Do you have initial or final temperatures or any other data?

-Mark
 
Start with the balanced reaction equation.
 
##\Delta H= \sum_i \nu_i \Delta H^0_{products}- \sum_j \nu_j\Delta H^0_{reactants}##

As Borek says, you should start by having the balanced chemical equation.
 
Last edited:
As Borek said, you have to start out with a balanced reaction equation. But you do realize that there is a reactant missing from the problem statement? Ask yourself, what is it the C6H5OH has to be reacting with to produce CO2 and H2O? (hint: it's a combustion reaction). So, what is the missing reactant. The next thing you have to recall is that, if this reactant is an elementary substance, what is its heat of formation? How is the heat of reaction related to the heats of formation of the products and the reactants?
 

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