[Rockhounds] concrete/cement - phosphoric acid

[Armando Afonso]

Coca-Cola has it in the composition, too!
I said it is toxic, right?
:)
Anyway, it could work, and I would like to know the result.


----- Original Message ----- 
From: "Axel Emmermann" <axel.emmermann at pandora.be>
To: "'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'" 
<rockhounds at lists.drizzle.com>
Sent: Tuesday, October 23, 2007 4:14 PM
Subject: RE: [Rockhounds] concrete/cement - phosphoric acid


> Household (kitchen) cleaning gels often have 1% or so phosphoric acid in
> them.
> Great for cleaning pyrite and even calcite.
> Brings great luster to shiny specimens.
> Don't let the calcite soak too long though! ;-)))
>
> Axel
>
>> -----Oorspronkelijk bericht-----
>> Van: rockhounds-bounces at lists.drizzle.com
>> [mailto:rockhounds-bounces at lists.drizzle.com] Namens J Bryan Kramer
>> Verzonden: dinsdag 23 oktober 2007 13:48
>> Aan: Rockhounds at drizzle.com: A mailing list for rock and gem
>> collectors
>> Onderwerp: Re: [Rockhounds] concrete/cement - phosphoric acid
>>
>> It may be slightly corrosive in the concentrated form, but it
>> isn't toxic.
>> And as mineral acids go, it isn't especially strong with a
>> PKa of +2, Citric acid has a PKa of +3 but a strong acid like
>> Hydrochloric has a PKa of -4. So it is slightly stronger than
>> Citric but 6 orders of magnitude weaker than HCl. The lower
>> the PKa, which is logarithmic, the stronger the acid.
>>
>> If you look on many soft drink labels you'll see phosphoric
>> acid is an ingredient, approved by the US FDA for human consumption.
>>
>> BK
>>
>> On 10/23/07, Armando Afonso <armandoafonso at oniduo.pt> wrote:
>> >
>> > A sugestion: Phosphoric acid is used to clean sewage pipes
>> of cement
>> > residues.
>> > Try it, with care. It is toxic!
>> >
>> >
>> >
>>
>>
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