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Re: Power Question - Was - Hydrometer Question ?

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  • Harry
    ... under 1.120. I guess Widder & Co. don t expect most washes to exceed SG 1.120. BTW, where did you get the specs for Prestige s Turbo? I went to Gert s
    Message 1 of 5 , May 3, 2005
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      --- In new_distillers@yahoogroups.com, Donald Ross
      <donald.ross@r...> wrote:
      >
      > Thanks Harry
      >
      > Your ISG figure of 1.122 definately explains my HD reading of
      under 1.120. I guess Widder & Co. don't expect most washes to
      exceed SG 1.120. BTW, where did you get the specs for Prestige's
      Turbo? I went to Gert's site (http://www.turbo-
      yeast.com/temperature.html) and found this:
      >
      > "Prestige 8 kg Turbo, Distillers Yeast and Pot Distillers Yeast
      > Start gravity 1120 (if you have the Oechslescale this is +120)
      > Final Specific gravity is 982 (if you have the Oechslescale this
      is -18)
      > You will have approx. 18% alcohol in the mash at 982......."
      >
      > That's why I was concerned when the HD went below 1.120.
      >
      > When you say it takes more power to break the chemical bond in the
      higher percentage alcolhol, do you have an approx. frame of
      reference in watts? IOW, would you need 750W for 18% abv as opposed
      to 500W for 10%? I'll be using a 1500W hot plate for this run and
      would like to know approx how far to cut it back once the wash comes
      to temperature.
      >
      > Cheers.....
      >
      > Don


      Yeast specs from Brewhaus site.

      re frame of reference. It doesn't quite work that way, Don.
      Adjusting the power is a "suck it & see" exercise, because it
      depends more on the characteristics of your particular still, and no
      two stills are the same. However, if you want to dabble your toes
      in some of the theory behind the molecular bonding I mentioned, then
      you need to have a look at Raoult's Law, Phase Diagrams, and the
      deviations from Raoult's Law as they apply to non-ideal mixtures
      (which ethanol:water is). This will get you started, without
      getting too scary. :-)
      http://www.chemguide.co.uk/physical/phaseeqia/nonideal.html


      Slainte!
      regards Harry
    • Robert Thomas
      Hi All, particularly Harry. ... http://www.chemguide.co.uk/physical/phaseeqia/nonideal.html ... Nice introduction to Raoult s law deviants! It doesn t say you
      Message 2 of 5 , May 3, 2005
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        Hi All, particularly Harry.
        You wrote about power/azeotropes and the like:


        > Adjusting the power is a "suck it & see" exercise,
        > because it
        > depends more on the characteristics of your
        > particular still, and no
        > two stills are the same. However, if you want to
        > dabble your toes
        > in some of the theory behind the molecular bonding I
        > mentioned, then
        > you need to have a look at Raoult's Law, Phase
        > Diagrams, and the
        > deviations from Raoult's Law as they apply to
        > non-ideal mixtures
        > (which ethanol:water is). This will get you
        > started, without
        > getting too scary. :-)
        >
        http://www.chemguide.co.uk/physical/phaseeqia/nonideal.html
        >

        Nice introduction to Raoult's law deviants!
        It doesn't say you need more power per mole in the
        case of stronger ethanol solutions.
        The only reason you need more power with stronger
        solutions is that you are vaporising more ethanol.
        The logical conclusion from your statement would be
        that it takes more power to boil 95percent ethanol
        than it does to boil 1percent. Surely not right.
        Any comments?
        Rob.

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      • Harry
        ... Exactly right, Robert. You can boil 95% ethanol all day, until you are blue in the face, but you won t separate the ethanol from the water. The lower the
        Message 3 of 5 , May 4, 2005
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          --- In new_distillers@yahoogroups.com, Robert Thomas
          <whosbrewing@y...> wrote:
          > Hi All, particularly Harry.
          > You wrote about power/azeotropes and the like:
          >
          >
          >
          > Nice introduction to Raoult's law deviants!
          > It doesn't say you need more power per mole in the
          > case of stronger ethanol solutions.
          > The only reason you need more power with stronger
          > solutions is that you are vaporising more ethanol.
          > The logical conclusion from your statement would be
          > that it takes more power to boil 95percent ethanol
          > than it does to boil 1percent. Surely not right.
          > Any comments?
          > Rob.


          Exactly right, Robert. You can boil 95% ethanol all day, until you
          are blue in the face, but you won't separate the ethanol from the
          water. The lower the ethanol content of the mixture, the easier it
          is to separate. If you look at the results of a phase diagram, like
          McCabe-Theile drawings, each stage or 'plate', IOW each distillation
          produces higher ethanol percentage, but the percentage increase for
          each stage from the last is less and less.

          A single water molecule can form hydrogen bonds between itself and
          up to four other water molecules. Vapor pressure varies with the
          strength of the intermolecular forces in the liquid. Ethanol can
          only form up to three hydrogen bonds, and they are not as strong as
          the hydrogen bonds in water.

          This tells us that if the mixture is mostly water, then the hydrogen
          bonds of the water will be harder to break than the hydrogen bonds
          of the ethanol, or the hydrogen bonds of the ethanol-water bond.

          I don't profess to be an 'expert' on this. Others may give you an
          easier explanation, but the fact remains. Ethanol is easier to
          separate from a water:ethanol solution lower in ethanol rather than
          higher.

          Slainte!
          regards Harry
        • Robert Thomas
          Hmmm, perhaps I m missing the point Harry; not unknown ;) ... Totally with you upto here. The lower the percentage ethanol (ie the further away from the
          Message 4 of 5 , May 4, 2005
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            Hmmm,
            perhaps I'm missing the point Harry; not unknown ;)
            --- Harry <gnikomson2000@...> wrote:
            > --- In new_distillers@yahoogroups.com, Robert Thomas
            >
            > <whosbrewing@y...> wrote:
            > > Hi All, particularly Harry.
            > > You wrote about power/azeotropes and the like:
            > >
            > >
            > >
            > > Nice introduction to Raoult's law deviants!
            > > It doesn't say you need more power per mole in the
            > > case of stronger ethanol solutions.
            > > The only reason you need more power with stronger
            > > solutions is that you are vaporising more ethanol.
            > > The logical conclusion from your statement would
            > be
            > > that it takes more power to boil 95percent ethanol
            > > than it does to boil 1percent. Surely not right.
            > > Any comments?
            > > Rob.
            >
            >
            > Exactly right, Robert. You can boil 95% ethanol all
            > day, until you
            > are blue in the face, but you won't separate the
            > ethanol from the
            > water. The lower the ethanol content of the
            > mixture, the easier it
            > is to separate. If you look at the results of a
            > phase diagram, like
            > McCabe-Theile drawings, each stage or 'plate', IOW
            > each distillation
            > produces higher ethanol percentage, but the
            > percentage increase for
            > each stage from the last is less and less.

            Totally with you upto here. The lower the percentage
            ethanol (ie the further away from the azeotopic mix),
            the more rapidly the approach to the azeotrope (ie the
            easier/faster the separation/concentration)

            >
            > A single water molecule can form hydrogen bonds
            > between itself and
            > up to four other water molecules. Vapor pressure
            > varies with the
            > strength of the intermolecular forces in the liquid.
            > Ethanol can
            > only form up to three hydrogen bonds, and they are
            > not as strong as
            > the hydrogen bonds in water.

            With you here also, though I don't believe the Hbond
            strengths are significantly different, given the
            vastly greater kinetic energy in the boiling mixture.
            They obviously must be somewhat different or there
            douldn't be a Raoult's deviation.

            >
            > This tells us that if the mixture is mostly water,
            > then the hydrogen
            > bonds of the water will be harder to break than the
            > hydrogen bonds
            > of the ethanol, or the hydrogen bonds of the
            > ethanol-water bond.

            Absolutely agree.

            >
            > I don't profess to be an 'expert' on this. Others
            > may give you an
            > easier explanation, but the fact remains. Ethanol
            > is easier to
            > separate from a water:ethanol solution lower in
            > ethanol rather than
            > higher.

            But that would imply that EtOH-EtOH H-bonding is
            stronger that EtOH-H2O H-bonding, meaning higher
            polarisation of the O-H bond in ethanol than water.
            This is wrong. The water OH bond is so polarised it is
            actually fluxional between covalent and ionic.

            Ah!! (lightbulb) hydrophobic forces coming into play.
            The Et moieties prefer to be together.

            Does adding salt to the wash make distillation easier?

            Anyway, having monologued my way to some sort of
            conclusion (sorry everyone, I missed out several lines
            of logical progression to get to here) I'd love to
            know the actual time/power differences between low and
            high pCent wash distillations.

            Oh, and yes Harry: you're right again, darn it!

            Cheers,
            Rob.

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