A Light Bulb Without Electricity-Catalytic Oxidation of Ammonia on a Copper Wire-Lu Le Laboratory

A Light Bulb Without Electricity

A copper coil is heated in the flame of a burner until it is glowing hot. The coil is suspended above a layer of ammonium hydroxide in a flask. The coil continues to glow and may eventually get hot enough to melt.

Mechanisms over copper catalyst

The XPS, EELS and STM techniques were used by the group of M.W. Roberts to study ammonia oxidation on copper surfaces. They observed that at very low

temperatures (< 300 K) ammonia could be oxidized to adsorbed NH2 and NH species

through oxydehydrogenation steps. At higher temperature (400 K) a fraction of the

imide species was further dehydrogenated into atomic nitrogen:

  

O + NH₃ → NH₂ + OH

O + NH₃ → NH + H₂O
O + NH → N + H₂O

The STM image clearly showed that the atomic nitrogen produced at 400 K could

block the ends of the –Cu-O- rows, inhibiting further reactions and creating stable

mixed N-O structures on the copper surface. Step defects on the surface had strong

influence on the reactivity of oxygen adatoms. Reactivity was high at the top and

bottom of a [110] step and at the bottom of a [001] step, whereas it was low at the top

of a [001] step.

Procedure

1.      Prepare a copper coil 1.5cm in diameter by winding a bare copper wire on a rob. Form a hook or any shape that can make the coil suspend.

 Use a smaller coil in a bigger vessel, it will glow longer

2.      Place 50~100mL of concentrated aqueous ammonia in a 1000mL Erlenmeyer flask.

3.      Heat the coil with a burner until it is glowing red-hot.

 

4.      Immediately place the coil in the flask, just above the level of the aqueous ammonia.

5.      Hook the end of the wire on the side of the flask.

6.      Observe the reaction.

 A Fascinating Glowing

7.      If the wire does not continue to glow, begin again using aqueous ammonia

  

Reference

1.      Chemical Demonstrations-A Sourcebook for Teachers/Volume1, Second Edition/Lee R. Summerlin and James L. Ealy, Jr./ American Chemical Society 1988/ ISBN:0-8412-1481-6

2.      Catalytic Oxidation of Ammonia to Nitrogen/Lu Gang http://alexandria.tue.nl/extra2/200210267.pdf