The NO/CS₂ Cannon

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Page ID: 3082

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Chemical Concepts Demonstrated

Complex stoichiometry
Exothermicity

Demonstration

A tube filled with NO gas is sealed with a rubber stopper.
CS₂ is quickly added to the tube (the demonstrator is careful not to allow any air to be admitted, since NO reacts with oxygen to form NO₂).
The tube is inverted to insure complete mixing.
The rubber stopper is then removed, and a lighted match is thrown down the tube.

Observations

As the match travels down the tube, a massive flame and a loud roar shoot forth from the top of the tube.

Explanation (include important chemical equations)

The reaction witnessed involves a very complex stoichiometry:

5 CS₂+ 10.8 NO -> 5.4 N₂+ 2.6 CO + 2.4 CO₂+1.7 SO₂+ 8.3 S

The reaction is first-order in CS₂and second-order in NO. The activation energy is 300 kJ/mol, which is the energy required to remove an S from CS₂. The energy released in this reaction is a whopping 3,280 kJ/mol.

Dr. George Bodner (Perdue University)