Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: PbO2 synthesis (not an anode)
MeshPL
National Hazard
****




Posts: 329
Registered: 20-4-2015
Location: Universe
Member Is Offline

Mood: No Mood

[*] posted on 28-4-2015 at 03:54
PbO2 synthesis (not an anode)


Ok. I've been wondering how can I synthetise PbO2. I may make an experimental anode but I need PbO2 powder. So I may need to synthetise it the following way:
1. Dissolve Pb in conc. NaOH to form plumbite.
2. Oxidise plumbite to lead dioxide with sodium persulphate.

Is it a good way to make PbO2? Or is there a better one? Using chlorine as oxidiser is not an option for me. Although I can buy PbO2, making some would be at least 3 times cheaper.
View user's profile View All Posts By User
jock88
International Hazard
*****




Posts: 505
Registered: 13-12-2012
Member Is Offline

Mood: No Mood

[*] posted on 28-4-2015 at 09:03


http://oxidizing.typhoonguitars.com/chlorate/leaddiox/makedi...

[Edited on 28-4-2015 by jock88]
View user's profile View All Posts By User
MeshPL
National Hazard
****




Posts: 329
Registered: 20-4-2015
Location: Universe
Member Is Offline

Mood: No Mood

[*] posted on 28-4-2015 at 12:19


Ok. Can I use acetate instead of nitrate? Or simply plumbite?
View user's profile View All Posts By User
sasan
Hazard to Self
**




Posts: 92
Registered: 22-2-2014
Location: TEHRAN / IRAN
Member Is Offline

Mood: Radiative

[*] posted on 24-11-2015 at 03:39



- Hey guys,I think the best way to make lead dioxide is here:
at first you should treat lead acetate or nitrate with sodium hydroxide solution to make lead hydroxide precipitate.

Then solve this precipitate in excess sodium hydroxide,this leads to soluble plumbate complexes with sodium,at the end pour excess of hydrogen peroxide solution to the plumbate complex solution.at the end you should see brownish black precipitate of PbO2.filter it and wash with water.
Ofcourse I hadn't tried this out but I'm sure this procedure will work.
View user's profile View All Posts By User
Boffis
International Hazard
*****




Posts: 1771
Registered: 1-5-2011
Member Is Offline

Mood: No Mood

[*] posted on 24-11-2015 at 06:42


The simplest method of preparing lead dioxide is to dissolve red lead (Pb3O4) in dilute nitric acid yielding lead dioxide and lead nitrate solution. The former is recovered by filtration and washed free of soluble lead salts.

Pb<sub>3</sub>O<sub>4</sub> + 4HNO<sub>3</sub> &rarr; PbO<sub>2</sub> + 2Pb(NO<sub>3</sub>;)<sub>2</sub> + 2H<sub>2</sub>O

The lead nitrate solution is also useful, it is readily crystallised and the solid lead nitrate used as a source of N<sub>2</sub>O<sub>4</sub>

You can also make it from old fashion white lead (basic lead carbonate) by dissolving in excess concentrated sodium hydroxide and adding hypochlorite bleach.
View user's profile View All Posts By User
AJKOER
Radically Dubious
*****




Posts: 3016
Registered: 7-5-2011
Member Is Offline

Mood: No Mood

[*] posted on 24-11-2015 at 15:06


To prepare PbO2 reasonably quickly (which I have successfully performed a few years ago), first create a soluble Pb salt like Lead acetate by placing an excess of Pb (Lead solder is one source) in a mixture of vinegar and dilute H2O2 together with a touch of sea salt (a good electrolyte). Jump start this electrochemical reaction (actually, a galvanic battery cell, no electrodes required unless ones want to harvest the electricity) with a short burst in a microwave (cover with plastic wrap to avoid inhaling any Lead fumes, which nevertheless remains the main hazard here). After an hour, with periodic reheating, you should have consumed the most of the vinegar and H2O2 having formed sufficient Lead acetate (in the amount of at most half the number of moles of acetic acid employed) to move on to the next step.

A much longer path, but less fume danger, is no heating or microwave and just let the reaction proceeded slowly over a week, as I did originally.

My take on the possible half reactions assuming similarity to the Zin-air battery (see https://en.m.wikipedia.org/wiki/Zinc%E2%80%93air_battery ), which in reality may not be precisely correct:

Anode: Pb + 2 OH- --> Pb(OH)2 + 2 e-

Cathode: H2O2 + 2 e- --> 2 OH-

Net cell: Pb + H2O2 --> Pb(OH)2

And, in the presence of acetic acid (HAc) and NaCl:

2 HAc + Pb(OH)2 --> PbAc2 + 2 H2O

Last step, to the aqueous Lead actetate, add chlorine bleach, NaClO (which is not much of a fume issue, in my opinion). A white precipitate of Lead hypochlorite, Pb(ClO)2 forms which on mild heating is converted into red PbO2. Source, please see http://bcs.whfreeman.com/WebPub/Chemistry/ichem5e/Videos/Hyp... , to quote:

"Initially, lead(II) ion reacts with hypochlorite ion to give a white precipitate of lead(II) hypochlorite:

Pb2++(aq) + 2 ClO-(aq) --> Pb(ClO)2(s)

The lead(II) hypochlorite is then oxidized to lead(IV) oxide. Reaction is slow at room temperature but much faster when the tube is placed in boiling water.

Pb2+(aq) + 2 H2O(l) --> PbO2(s) + 4 H+(aq) + 2 e-

ClO-(aq) + 2 H+(aq) + 2 e- --> Cl-(aq) + H2O(l) "

[Edited on 24-11-2015 by AJKOER]
View user's profile View All Posts By User

  Go To Top