21 replies to this topic

[newtoolsmith]

Hi friends,

I am going to cover graphite elektrodes (7,5x300mm) with lead dioxide to use them in chlorate and perchlorate cells.

Therefore lead nitrate and copper nitrate are needed. So I put about 6mol lead into a can with almost 12mol HNO3. I wanted all the acid to be used and a bit of the lead to be left.

So I did and - nothing happened. This was two days ago and I cant say that significant nitrate was formed.

Is there a need to heat the stuff to make the HNO3 more reactive? The PbO was removed more or less from the surface of the lead.

If needed to be heatened, will it be enough to heat the can (made from PE) in a hot water bath? I have no glass pot witch would resist heat. Too insecure.


The same question about the copper nitrate. This should be formed by bringing copper and HNO3 together, shouldnt it?

Pure copper and lead are the first choice as they are available in large amounts...and so is HNO3.

MfG
newtoolsmith

[newtoolsmith]

Noone has any idea?

Unvbelieveable!

BigG!!!!!!!!!!!!

MfG
newtoolsmith

[pyrotrev]

It's been a long time since I did this so please excuse if I'm a bit rusty (sorry, oxidised
). If my memory serves me well, metallic lead won't react directly with cold HNO3, you'd be better off with oxide/carbonate, however it does react with hot conc. HNO3. Water bath heating is nearly always a good idea, but I'm not sure about the stability of PE in hot, conc. HNO3.....remember it is a SERIOUS oxidiser.Copper does dissolve in cold, fairly conc. HNO3, but you get quite a lot of (brown) NO2 fumes, so take suitable precautions.

Stay green

(but not because you're covered in copper compounds, please )

[EnigmaticBiker]

Noone has any idea?

Unvbelieveable!

BigG!!!!!!!!!!!!

MfG
newtoolsmith

Hang on, I'll get my books out!

sasman may be able to help, his electrolysis equipment is really extensive (elsewhere on this forum).

Be very careful using PE it is likely to get very soft if heated, some grades melt at 120 C.
Borosilicate (Pyrex in UK) glass bowl would be better.

Simon

[EnigmaticBiker]

Pure copper and lead are the first choice as they are available in large amounts...and so is HNO3.

MfG
newtoolsmith

Lead Nitrate.

Using the metal is mentioned, but as you suggested, would need to be heated. Grinding up the lead would help but still means boiling conc HNO3 - Very dangerous, I wouldn't attempt it.

A possible source for fairly pure oxide is "red lead" Pb3O4, occasionally used in paints. With HNO3 this gives:-
Pb3O4 + 4(HNO3) ---> 2(Pb(NO3)2) + PbO2 + H2O

Another is Litharge PbO, used in glass and pottery glazes. PbO + 2(HNO3) ---> Pb(NO3)2 + H2O

Impure sources include:-
The mineral Cerrusite PbCO3,
The mineral Galena PbS and even heating the contents of lead-acid batteries, removing the molten lead, should leave a slag of PbSO4 and oxides, roasting this should give oxides. It will be contaminated with antimony. This process releases very toxic and corrosive gases.

Hope that helps,

Simon

Edited by EnigmaticBiker, 22 February 2006 - 09:54 PM.

[newtoolsmith]

I did it!!

In a stainless steel pot I heated some water and, with two wooden sticks under it, I put the can into the pot. I did it this way because I wasnt sure if the steel would resist the hot acid.

When headed to about 60 or 70 degrees (was too hot to touch and I am not afraid of heat...) some bubbles of H2 began to come up. Fine.

The can got quite soft but didnt break or melt. Oxidation wasnt noticed either.

I then let cool this down and after three hours I filled the mixture from the can into the (empty) pot and cooked it again. Much NO2 occured - that will be the reason why onla half or 2/3 of the measured lead has reacted with the acid.

Tomorrow I will recristallyse and see how it worked.

Thanks for your tips!!

MfG
newtoolsmith

Edited by newtoolsmith, 22 February 2006 - 10:50 PM.

[EnigmaticBiker]

I did it!!

In a stainless steel pot I heated some water and, with two wooden sticks under it, I put the can into the pot. I did it this way because I wasnt sure if the steel would resist the hot acid.

When headed to about 60 or 70 degrees (was too hot to touch and I am not afraid of heat...) some bubbles of H2 began to come up. Fine.

The can got quite soft but didnt break or melt. Oxidation wasnt noticed either.

Glad you managed it OK.

Out of curiosity. was the PE can clear and uncoloured (no fillers or pigments)?

Simon

[newtoolsmith]

Indeed, the PE seemed to contain no additives. And it really was clear, now its light brown but seems to be still in very good condition. Probably just something cocoured on the surface.

This morning the result was visible: lots of light yellow crystals wich will be recrystallised today.

MfG
newtoolsmith

[EnigmaticBiker]

Indeed, the PE seemed to contain no additives. And it really was clear, now its light brown but seems to be still in very good condition. Probably just something cocoured on the surface.

This morning the result was visible: lots of light yellow crystals wich will be recrystallised today.

MfG
newtoolsmith

I thought so, most fillers are metal oxides or carbonates which could have reacted.
PE is very stable generally, one unusual property is stress cracking, often caused by harmless detergents!

My guess is that they are yellow from iron III nitrate.

Simon

[newtoolsmith]

Hi friends,

I was wrong:

The crystals are not yellow at all - they are brite white!! Whiter than white and shining like diamonds. The liquid above is the yellow thing.

When you stirr the crystals, which are very small, and the liquid together, it looks like yellow-gold-metallic-effect-laquer. (what a word). Looks really beautiful.

Today I started making copper nitrate too. The copper reacts even at perhaps two degrees celsius with the nitric acid as you can see from the escaping H2 bubbles. No heating necessary. The solution gets nice blue.

Pyrotechnics produce nice colours in many ways...

Further infos will follow.

MfG
newtoolsmith

[EnigmaticBiker]

Pyrotechnics produce nice colours in many ways...

Yes, I find chemical crystals fascinating and beautiful.

Simon

[newtoolsmith]

The lead and copper nitrates are finished now. I didnt dry them completely because I dont want any leadnitrate dust to fly around. Too toxic.

Theese days I am constructing a heavy power supply* to get the electrolysis started...

MFG
newtoolsmith


*heavy? 0...40V stabilized; 100A@6V; 80A@8V; 16A@40V - that should be enough for perc manufacture, right?

[leosedf]

Does anyone know how to make lead tetraoxide? I tryed to mix it up with NaOH but nothing happened. Anything i am missing?

thnx

[TheChemist]

Does anyone know how to make lead tetraoxide? I tryed to mix it up with NaOH but nothing happened. Anything i am missing?

thnx

Before I dig into all of my books, is it the Pb3O4 you are interested in? (This is red and has been used as colour in paint) or the PbO2, a powerful oxidizer that can be used in matches together with red phosphorus.

[leosedf]

Only Pb3O4....

Dragon eggs

Thank you.

Edited by leosedf, 10 November 2006 - 08:36 AM.