Calculate Energy Change for CO + Cl2 Reactions - Help!

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Discussion Overview

The discussion revolves around estimating the energy change associated with the reaction of carbon monoxide (CO) and chlorine (Cl2) to form phosgene (Cl2CO). Participants explore different methods for calculating this energy change, including the use of bond energies and calorimetry, while expressing uncertainty about the correct approach.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants express uncertainty about how to estimate the energy change for the reaction, indicating they have ideas but are unsure if they are correct.
  • One participant questions whether enthalpies of formation or bond dissociation energies are provided for the calculation.
  • Another suggests using a calorimeter to measure temperature changes during the reaction as a method to estimate energy change.
  • Several participants propose using bond energy values to estimate the reaction energy, detailing the changes in bond types and energies involved in the reaction.
  • One participant calculates an estimated reaction energy of approximately 128 kJ/mol based on bond energy differences, while noting variability in bond energy data.
  • Another participant provides a different estimate of -100 kJ/mol by comparing the sum of average bond energies for reactants and products, but does not clarify the basis for this calculation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct method or value for the energy change, with multiple competing views and calculations presented throughout the discussion.

Contextual Notes

There are limitations regarding the assumptions made about bond energies, the potential variability in data, and the lack of clarity on the specific values used in calculations.

claudzterz9
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I am not sure how to find this... estimate the energy change that occurs when carbon monoxide and chlorine combine to make phosgene...

CO(g) + Cl2(g) ---> Cl2CO(g)

i have an idea of what to do,except i think its not the right way.
 
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They do not give enthalpies of formation or Bond dissociation energies?
 
claudzterz9 said:
I am not sure how to find this... estimate the energy change that occurs when carbon monoxide and chlorine combine to make phosgene...

CO(g) + Cl2(g) ---> Cl2CO(g)

i have an idea of what to do,except i think its not the right way.

Maybe you want to have a look to the thread " Enthalpy change and activation energy".
 
claudzterz9, you can do that by reacting CO and Cl2 in a calorimeter, by measuring temperatures before and after reaction.
 
take the bond energy values from your data booklet...
 
claudzterz9 said:
I am not sure how to find this... estimate the energy change that occurs when carbon monoxide and chlorine combine to make phosgene...

CO(g) + Cl2(g) ---> Cl2CO(g)

i have an idea of what to do,except i think its not the right way.

If your problem is to estimate it from given bond energies, as Kushal wrote, then in the reaction

CO(g) + Cl2(g) ---> COCl2(g)

1. You go from a triple bond in CO to a double bond between C and O in COCl2; so you have to compute this difference of energy.
2. You loose a Cl-Cl bond and you gain 2 C-Cl bonds

So, calling E1 the energy of the triple bond between C and O, E2 the energy of double bond between C and O in phosgene, E3 the bond energy Cl-Cl and E4 the bond energy C-Cl, you have, as estimated reaction energy:

E2 - E1 + 2E4 - E3 ~ 128 kJ/mol with the data I've found (but remember there is quite variation on these kind of data).

Edit. The reaction enthalpy is the same but with sign changed.
 
Last edited:
lightarrow said:
If your problem is to estimate it from given bond energies, as Kushal wrote, then in the reaction

CO(g) + Cl2(g) ---> COCl2(g)

1. You go from a triple bond in CO to a double bond between C and O in COCl2; so you have to compute this difference of energy.
2. You loose a Cl-Cl bond and you gain 2 C-Cl bonds

So, calling E1 the energy of the triple bond between C and O, E2 the energy of double bond between C and O in phosgene, E3 the bond energy Cl-Cl and E4 the bond energy C-Cl, you have, as estimated reaction energy:

E2 - E1 + 2E4 - E3 ~ 128 kJ/mol with the data I've found (but remember there is quite variation on these kind of data).

Edit. The reaction enthalpy is the same but with sign changed.

the answer u r looking for is -100 KJ/mol...

how i got it is by lookin at the avg bond energies for the reactants and the sum for that is 1310 and then i lloked for the the sum of the avg bond energies for the product whih is 1410...

subtract the 2 and you get -100 kj/mol
 

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