Question

Given a reaction and enthalpies of combustion, how does one indirectly calculate enthalpy of reaction? i.e.,...

Given a reaction and enthalpies of combustion, how does one indirectly calculate enthalpy of reaction? i.e., if I take stoichiometric coefficients into account and subtract reactant combustion enthalpies from products, I end up with an overall combustion enthalpy for the reaction. How does this relate to enthalpy of reaction? Is it the same?

Science   Chemistry   
0 0
Add a commentTranscribed image text
Next >

Homework Answers

Answer #1

Let us take an example of the combustion of methane.

CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l)

The enthalpy of reaction enthalpy of reaction Hrxn is given as sum of Hformation (products) - sum of Hformation (reactants)

Where Hformation is the enthalpy change of formation of the compound.

So, Hrxn = Hformation (products) - Hformation (reactants)

Hrxn = Hformation(CO2(g) ) + 2*Hformation(H2O(l)) - ( Hformation(CH4(g)) + 2*Hformation(O2(g)) )

As you can see for the overall enthalpy of combustion of the CH4 is same as enthalpy of reaction of combustion of CH4

If Hformation of reactant or products is not given directly we may need to get it by the individual reactions of each of them.

For example for H2O its

H2(g) + (1/2)O2(g) -> H2O(l)

Hformation(H2O(l)) = 2*Bond energy of H-O - (Bond Energy of H2(g) in H-H + (1/2)*Bond energy of O2(g) in O=O)

0 0
Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
1. Enthalpies and energies of reactions. Consider the combustion of methane, which involves the reaction of...
1. Enthalpies and energies of reactions. Consider the combustion of methane, which involves the reaction of 1 mol CH4(g) with 2 mol of O2(g) to form 1 mol CO2 (g) and 2 mol H2O (l): CH4(g) + 2 O2(g) → CO2(g)+ 2 H2O(l) (a) Using heats of formation from Table 2.6 in the text (or from the tables in the back of the book, or from webbook.nist.gov) calculate ∆Hr◦ for the reaction. (b) Calculate ∆Ur for the reaction by only...
Calculate the enthalpy of combustion. Write a balanced combustion reaction for the oxidation of your substance...
Calculate the enthalpy of combustion. Write a balanced combustion reaction for the oxidation of your substance to CO2 and H2O. From the stoichiometry of this reaction and the amount of sample you used, find delta(PV) and thus calculate deltaH. Compare your value of deltaH with the literature value. deltaH = deltaU + delta(nRT) = delta U + RT(delta n). the combustion equation is C12H22O11(s)+12O2(g)arrow12CO2(g)+11H2O(l) for sucrose. There are 0.1544g of sucrose combusted in a constant volume calorimeter. Please explain and...
Constants | Periodic Table Learning Goal: To understand how standard enthalpy of reaction is related to...
Constants | Periodic Table Learning Goal: To understand how standard enthalpy of reaction is related to the standard heats of formation of the reactants and products. The standard enthalpy of reaction is the enthalpy change that occurs in a reaction when all the reactants and products are in their standard states. The symbol for the standard enthalpy of reaction is ΔH∘rxn, where the subscript "rxn" stands for "reaction." The standard enthalpy of a reaction is calculated from the standard heats...
Calculate the enthalpy of the reaction 2NO(g)+O2(g)→2NO2(g) given the following reactions and enthalpies of formation: 12N2(g)+O2(g)→NO2(g),   ΔH∘A=33.2...
Calculate the enthalpy of the reaction 2NO(g)+O2(g)→2NO2(g) given the following reactions and enthalpies of formation: 12N2(g)+O2(g)→NO2(g),   ΔH∘A=33.2 kJ 12N2(g)+12O2(g)→NO(g),  ΔH∘B=90.2 kJ
1.) Using enthalpies of formation, calculate the standard change in enthalpy for the thermite reaction. The...
1.) Using enthalpies of formation, calculate the standard change in enthalpy for the thermite reaction. The enthalpy of formation of Fe3O4 is −1117 kJ/mol. 8 Al(s) + 3 Fe3O4(s) → 4 Al2O3(s) + 9 Fe(s) 2. a) Nitroglycerin is a powerful explosive, giving four different gases when detonated. 2 C3H5(NO3)3(l) → 3 N2(g) + 1/2 O2 (g) + 6 CO2(g) + 5 H2O(g) Given that the enthalpy of formation of nitroglycerin, ΔHf°, is −364 kJ/mol, calculate the energy (heat at...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of one mole of substance from its constituent elements in their standard states. Thus, elements in their standard states have ΔH∘f=0. Heat of formation values can be used to calculate the enthalpy change of any reaction. Consider, for example, the reaction 2NO(g)+O2(g)⇌2NO2(g) with heat of formation values given by the following table: Substance ΔH∘f (kJ/mol) NO(g) 90.2 O2(g) 0 NO2(g) 33.2 Then the standard heat...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of one mole of substance from its constituent elements in their standard states. Thus, elements in their standard states have ΔH∘f=0. Heat of formation values can be used to calculate the enthalpy change of any reaction. Consider, for example, the reaction 2NO(g)+O2(g)⇌2NO2(g) with heat of formation values given by the following table: Substance   ΔH∘f (kJ/mol) NO(g)   90.2 O2(g)   0 NO2(g)   33.2 Then the standard heat...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of one mole of substance from its constituent elements in their standard states. Thus, elements in their standard states have ΔH∘f=0. Heat of formation values can be used to calculate the enthalpy change of any reaction. Consider, for example, the reaction 2NO(g)+O2(g)⇌2NO2(g) with heat of formation values given by the following table: Substance ΔH∘f (kJ/mol) NO(g) 90.2 O2(g) 0 NO2(g) 33.2 Then the heat of...
Please solve for only problem 2. The first problem is needed for the 2nd one. Please...
Please solve for only problem 2. The first problem is needed for the 2nd one. Please show all work and thank you. 1.) Oxidative dehydrogenation of ethane is the conversion of ethane with oxygen to yield ethylene and water. It is a cleaner and more efficient alternative to the widely used steam cracking process for ethylene production from ethane. a. Write down the (balanced) reaction equation, and list (separately) the stoichiometric coefficients for all reactants and products. Assuming that you...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of...
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of one mole of substance from its constituent elements in their standard states. Thus, elements in their standard states have ΔH∘f=0. Heat of formation values can be used to calculate the enthalpy change of any reaction. Consider, for example, the reaction 2NO(g)+O2(g)⇌2NO2(g) with heat of formation values given by the following table: Substance ΔH∘f (kJ/mol) NO(g) 90.2 O2(g) 0 NO2(g) 33.2 Then the standard heat...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT