Equilibrium of NO2 and N2O4

 

Materials: 

Two sealed NO2 (gas) equilibrium tubes

4 liter beaker of ice water

4 liter beaker of hot water

Hotplate

 

Procedure: 

Place one tube in an ice bath and place a lid on top

Use one tube as room temperature standard.

Place a third tube in a hot water bath and place a lid on top.

After a few minutes compare the color in the tubes.

 

Discussion: 

Heat shifts the equilibrium in favor of NO2 and the tube becomes darker.  Since the formation of N2O4 is an exothermic reaction, lowering the temperature shifts the equilibrium in favor of colorless N2O4.  In a dry ice - acetone bath, the N2O4 will crystallizes as a white solid.

 

 

ΔHf (KJ/Mol)
S (J/K*Mol)
ΔGf (KJ/Mol)
NO2
33.2
240.1
51.3
N2O4
11.1
304.4
99.8

 

 

 

To schedule a demonstration, please send an email to the demonstration lab.

 

Contact:

Eric Camp

Lecture Demonstration Technician

Bagley Hall 171

(206) 543-1606

ericcamp@uw.edu

 

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