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

Make Pure Nitrocellulose - Nitration - Lu Le Laboratory

Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it was originally known as guncotton. Nitrocellulose plasticized by camphor was used by Kodak, and other suppliers, from the late 1880s as a film base in photograph, X-ray films and motion picture films; and was known as nitrate film. After numerous fires caused by unstable nitrate films, safety film started to be used from the 1930s in the case of X-ray stock and from 1948 for motion picture film.

 Units of Nitrocellulose

Units of Nitrocellulose in 3D

 

In this experiment, we are going to use a strong nitrating agent, Sulfonitric Mixed Acid. In the SNMA (Sulfonitric Mixed Acid), NO₂⁺ ion is a very strong acid, and it would react with –OH group and from –O-NO₂ group. The nitro group is a strong oxidizing group, it makes organic compound burns faster and even explode.

The reactions of the SMA are as follow:

Reaction of the SNMA:

Reaction of NO₂⁺ with R-OH:

Side Reaction:

Mix the two acid together is quite an exothermic reaction To prevent the nitric acid decomposes into NO₂ and sulfuric acid decompose the cellulose, keep the temperature of mixture below 5℃.

Chemical

1.      Cotton wool: ~2g

 

2.      70% nitric acid: 25mL

3.      98% sulfuric acid: 25mL

4.      NaHCO₃ saturated solution: ~ 200mL

5.      Clean water: ~ 1L

 

Procedure

1.      Place 25mL 70% nitric acid into a Erlenmeyer flask and put it in an ice bath to cool down below 5℃.

 The Erlenmeyer flask an nitric acid ice bath

 2.      Add 25mL 98% sulfuric acid into the flask gently, and stir it thoroughly.  Stand the mixture about a minute to let more NO₂⁺ from. Notice the temperature of the mixed acid should not excess 5℃.

 The Sulfonitric Mixed Acid looks a little yellow

 

3.      Place 2.17g cotton ball in the mixed acid, and insure the cotton is totally soaked in the mixed acid (squeeze the air out inside the cotton ball with a glass rob).

 Cotton wool in the SNMA, this yellow color is because of Sulfonation but not decomposition of the cellulose

4.      Let the cotton reacts about 20 minutes(also <5℃ or the cotton would turn yellow because of the decomposition that sulfuric acid caused).

5.      Decant the mixed acid out, and pour some iced water into the Erlenmeyer flask to wash the acid inside cotton. Shake the Erlenmeyer flask to insure the water really defuse in the cotton. Repeat the step 2~3 times.

 Decant the mixed acid out

Use clean water wash the cotton

The cotton wool turn back to white because of the side reaction 

6.      Use some saturated NaHCO₃(baking soda) solution to wash the cotton until no more bubbles form.

 Saturated soda water

 Bubbles are forming

The solution stop bubbling

 

7.      Use plenty clean water to wash the cotton until the pH value of the water-cotton mixture is located under 6.80~7.20

 Wash it times and times

It has a perfect pH value

 

8.      Squeeze water out from the cotton, and put the cotton in a desiccator.

9.      Weight the cotton, and figure out the assay, percentage of nitrogen

 The dried final preduct, 94.2% nitrocellulose.

Testing

 

Analysis

 

Weight of Cotton Wool	2.17g
pH Value of the mixture of water-cotton	6.88~7.01
Weight of Product(Theory)	2.17 * (297(g/mole)/162(g/mole)) = 3.98g
Weight of dried final product	3.81 g
Percentage of NC (nitrocellulose) [Set the X=mole of NC 3.81g = (162 * (2.17/162-X)+ 297*X) => X= 0.0121 (0.0121/0.0134)*100% = 94.2% ]	94.2%
Percentage of Nitrogen(by weight)	13.3%
Grade:	Explosive