How do I know which enthelpy change to calculate?

  • Thread starter Thread starter Physicsman788
  • Start date Start date
  • Tags Tags
    Change
Click For Summary
Determining whether to find the enthalpy of combustion or the enthalpy of formation depends on the specific context of the question. The enthalpy of combustion refers to the energy change when one mole of a substance is completely burned in oxygen under standard conditions, while the enthalpy of formation is the energy change when one mole of a compound is formed from its elements in their standard states. Understanding the requirements of the question is crucial, as there is no universal approach; each scenario will dictate which enthalpy value is needed based on the substances involved and the reactions being considered.
Physicsman788
Messages
3
Reaction score
0
How do I know if I need to find the enthalpy of combustion or the enthalpy of formation? I know the equation to find the enthalpy change of each them but I don't know on a question if I have to find the enthalpy of combustion or the enthalpy of formation.
 
Chemistry news on Phys.org
It must depend on the question, there is no "one size fits all" answer.
 
Reply
  • Like
Likes Chestermiller
The standard enthalpy change of combustion of a compound is the enthalpy change which occurs when one mole of the compound is burned completely in oxygen under standard conditions, and with everything in its standard state.

https://www.chemguide.co.uk/physical/energetics/definitions.html
 

Thread 'Molecular-level explanation of macroscopic phenomena: dissolving'

What I know and please correct me: a macroscopic probe of raw sugar you can buy from the store can be modeled to be an almost perfect cube of a size of 0.7 up to 1 mm. Let's assume it was really pure, nothing else but a conglomerate of H12C22O11 molecules stacked one over another in layers with van de Waals (?) "forces" keeping them together in a macroscopic state at a temperature of let's say 20 degrees Celsius. Then I use 100 such tiny pieces to throw them in 20 deg water. I stir the...
View full post »

Similar threads

What is the heat of combustion of 1 kg carbon dioxide w/ magnesium?
  • · Replies 2 ·
Replies
2
Views
2K
Standard enthelpies of formation of carbon nanotubes etc.
  • · Replies 2 ·
Replies
2
Views
2K
Enthelpy vs Internal Energy in Phase Change
  • · Replies 12 ·
Replies
12
Views
5K
Enthelpy of combustion of acetylene and fluorine
  • · Replies 2 ·
Replies
2
Views
2K
Change in Free Energy when Heating a Substance
  • · Replies 9 ·
Replies
9
Views
3K
Chemistry Does Combusting Different Amounts of Propane Change Final Temperature?
  • · Replies 5 ·
Replies
5
Views
2K
Need Help understanding energy and enthelpy please
  • · Replies 6 ·
Replies
6
Views
2K
How is enthelpy different than heat?
  • · Replies 2 ·
Replies
2
Views
3K
Change in Enthelpy for Nitrogen at constant temp
  • · Replies 6 ·
Replies
6
Views
3K
Enthelpy of Formation of Tetraoxygen
  • · Replies 4 ·
Replies
4
Views
3K