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Re: [Homebrew_PCBs] Re: air sparger for cupric chloride etchant and supplies

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  • Adam Seychell
    ... Something like that. but I think the porous hose works better. Aquarium air stones are good too. ... From the chemical chart, Tygon seems ok in most acids.
    Message 1 of 9 , Mar 31, 2003
      grantfair2001 wrote:
      > Thanks for the additional information. Did you use the pipe layout
      > which Think and Tinker recommends, like a U shape, with the PCB in the
      > middle between the "legs" (if that makes any sense at all)?

      Something like that. but I think the porous hose works better.
      Aquarium air stones are good too.

      >
      > The air tubing I have on hand is Tygon F-4040 A. I know little about
      > it except it's cheap at my local surplus store and I believe it is
      > fairly non-reactive to most chemicals. (Please correct me if I am wrong.)
      >

      From the chemical chart, Tygon seems ok in most acids. I know
      that solid nylon just crumbles apart after a week in 20%(w/w)
      sulfuric acid. The only problem with the soft clear PVC tubing is
      it tends to become tacky on the surface after a few weeks. It
      doesn't seem to penetrate very far.


      > For air I thought I would try a portable tire inflator from Harbor
      > Freight, or perhaps an old Gast vacuum pump I've had kicking around
      > for years, if I can figure out how to use it as a compressor. Failing
      > that a buddy has offered an aquarium pump but my etch tank is a 34
      > quart capacity Coleman chest cooler, so I am unsure it will have the
      > needed air volume.

      Try it and see. sewerage treatment aeration pumps are perfect for
      the job. I should look on the secondhand market. Last time I
      checked a new Nitto Kohki 80L/min pump was about $500.
      A 'large' aquarium pump might be 2L/min

      >
      > I have also found some cheap 1/2 mL pipettes (C$ .25) and a surplus
      > 100 ml cylinder specified to +/- 1 ml (C$ 7), which seems like it
      > would be fine for measuring for titration, since the article suggests
      > results within +/- 10% are fine for adjusting the acid level. I am
      > hoping a student burette will do the trick since, so far the best
      > proice for a legit version will set me back $140 Can.
      >
      CA$140 sounds expensive. Here in Australia a lab place near me
      sells "Brand" 50ml (class B) burettes for AU$70. Still, expensive
      so you might want to have a better look around. Pipettes are not
      terribly expensive, around AU$4 to $6. Order as many free
      catalogs as you can.

      > Also- anyone know of a reasonably priced source of bromophenol blue?
      > So far the best I have seen is C$ 65.00 for 5 grams of ACS grade. That
      > seems like an awful high price, and if a lab grade is available I
      > assume that would work ok.

      Yep, that sounds about right. I think the best thing for you to
      do is post that question on sci.chem news group explaining you
      are titrating HCl in cupric chloride. approx. strengths 1 Molar
      and can accept few percent error. I am using methyl orange with
      good success.
    • grantfair2001
      Thanks for the additional info, Adam. What kind of methyl orange are you using - aqueous? What percent, 0.1% or....? (MO seems to be more readily available
      Message 2 of 9 , Apr 2, 2003
        Thanks for the additional info, Adam. What kind of methyl orange are
        you using - aqueous? What percent, 0.1% or....?

        (MO seems to be more readily available than bromophenyl blue and not
        too pricey). What is the shelf life of the stuff?

        I haven't figured out how to access usenet groups with my current
        setup, so MO seems the easiest way to go.

        Grant

        --- In Homebrew_PCBs@yahoogroups.com, Adam Seychell
        <adam_seychell@y...> wrote: [snip]

        > Yep, that sounds about right. I think the best thing for you to
        > do is post that question on sci.chem news group explaining you
        > are titrating HCl in cupric chloride. approx. strengths 1 Molar
        > and can accept few percent error. I am using methyl orange with
        > good success.
      • Adam Seychell
        ... don t know about shelf life, its from my chemistry set that I got when I was a kid (~ 20 years ago) and its works fine. The indicator solution I use is
        Message 3 of 9 , Apr 3, 2003
          grantfair2001 wrote:
          > Thanks for the additional info, Adam. What kind of methyl orange are
          > you using - aqueous? What percent, 0.1% or....?
          >
          > (MO seems to be more readily available than bromophenyl blue and not
          > too pricey). What is the shelf life of the stuff?
          >
          don't know about shelf life, its from my chemistry set that I got
          when I was a kid (~ 20 years ago) and its works fine.
          The indicator solution I use is about 0.1% I think. Not
          important, just enough to look nice and colorful.
          As far as I know, the different indicators are used depending on
          pH you want them to change at. For HCl and NaOH titration I think
          almost any can be used because the pH change near the end point
          is very dramatic as it passes neutral. Its because NaOH is a
          strong base and HCl is a strong acid, which means they ionize
          completely in water which means there is no free NaOH or HCl
          molecules in the solution instead they exist almost entirly of as
          ions, Na+, OH- or H+ and Cl-.


          In aquious solutions the concentrations (in moles per liter) of
          H+ and OH- ions are always at equilibrium according to

          [H+] * [OH-] = 10E-14

          where [H+] is concentration of H+ ions in moles per liter.
          [OH-] is concentration of OH- ions in moles per liter.

          so if you add H+ ions to water then there automatically has to be
          less OH- ions for the above equation to balance.

          now pH is defined as -log10 ([H+])

          in pure water [H+] must equal [OH-] and so
          [H+] = [OH-] = 10E-7
          pH of pure water then is equal to -log10(10E-7) = 7

          [H+] of 10E-7 is a small number so if you add tiny bit of HCl to
          pure water then [H+] goes sky high and so pH drops down a lot.
          The same goes for NaOH and water ,except [OH-] goes sky high
          which means [H+] must get a lot smaller than 10E-7 to keep the
          equation balanced. Hope this makes some sense.

          here is some stuff on indicators

          http://ecommerce.hach.com/stores/hach/pdfs/wah/eng_pdf/ex_pHindicators.pdf

          Notice in figure 1 showing the dramatic pH change



          If you really interested then I'd recommend getting hold of a
          secondhand copy of a good 1st year chemistry book and learn about
          solution equilibrium.

          Adam






          > I haven't figured out how to access usenet groups with my current
          > setup, so MO seems the easiest way to go.
          >

          use http://groups.google.com
          as a web based NNTP browser and for posting.
        • bhaskaran chidambaram
          i want info about oscillators and their functioning.if anyone has the material pls send it tnx Catch all the cricket action. Download Yahoo! Score tracker
          Message 4 of 9 , Apr 3, 2003
            i want info about oscillators and their functioning.if anyone has the material pls send it

            tnx





            Catch all the cricket action. Download Yahoo! Score tracker

            [Non-text portions of this message have been removed]
          • Steve Greenfield
            This would be on topic for lists such as Electronics_101 and Advanced_Electronics. http://groups.yahoo.com/group/Electronics_101
            Message 5 of 9 , Apr 4, 2003
              This would be on topic for lists such as Electronics_101 and
              Advanced_Electronics.

              http://groups.yahoo.com/group/Electronics_101

              http://groups.yahoo.com/group/Advanced_Electronics

              Steve, the moderator

              --- bhaskaran chidambaram <bhaskaran_india@...> wrote:
              >
              > i want info about oscillators and their functioning.if anyone has
              > the material pls send it
              >
              > tnx

              =====
              Steve Greenfield // Digital photography, scanning,
              Polymorph Digital Photography // retouching, and photomorphing
              253/318-2473 voice // to your specs.
              polymorph@... //
              http://www.polyphoto.com/ // Based in Tacoma, WA, USA

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