Calculate Enthalpy Change: C6H5OH, CO2, H2O

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In summary, the problem involves determining the change in enthalpy for a combustion reaction using the enthalpies of formation for the reactants and products. The missing reactant is oxygen and the heat of reaction is related to the heats of formation through a balanced reaction equation.
  • #1
iRaid
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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)


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The Attempt at a Solution


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

Any direction is appreciated.
 
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  • #2
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
 
  • #3
Start with the balanced reaction equation.
 
  • #4
##\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.
 
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  • #5
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?
 

1. What is the equation for calculating enthalpy change?

The equation for calculating enthalpy change is ∆H = ∑(n∆Hp), where ∆H is the enthalpy change, n is the number of moles of the substance, and ∆Hp is the standard enthalpy of formation for each substance involved in the reaction.

2. How do you calculate the standard enthalpy of formation (∆Hp) for a substance?

The standard enthalpy of formation for a substance can be found in reference tables or by using the Hess's Law equation, which states that the enthalpy change for a reaction is equal to the sum of the enthalpy changes for each step of the reaction.

3. Can you provide an example of calculating enthalpy change for a specific reaction?

Yes, for the reaction C6H5OH + 7/2O2 → 6CO2 + 3H2O, the enthalpy change can be calculated by first finding the standard enthalpy of formation for each substance, then plugging those values into the enthalpy change equation.

4. How do you know if a reaction is exothermic or endothermic based on the enthalpy change value?

If the enthalpy change is negative, the reaction is exothermic, meaning energy is released in the form of heat. If the enthalpy change is positive, the reaction is endothermic, meaning energy is absorbed in the form of heat.

5. Are there any other factors that can affect the enthalpy change of a reaction?

Yes, the temperature, pressure, and concentration of reactants can also affect the enthalpy change of a reaction. Additionally, any changes in the physical state of the reactants or products can also impact the enthalpy change.

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