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-   -   Where's Bill Nye when I need him? (http://www.plantedtank.net/forums/20-diy/202754-wheres-bill-nye-when-i-need-him.html)

dprais1 12-29-2012 06:36 PM

Where's Bill Nye when I need him?
 
I have a pop bottle for my DIY CO2. First couple of days I get crazy amount of little bubbles in my tank. Then it levels off and stays that way 24/7. If i jostle the bottle a little bit a get a 3-5 second 'burst'

BUT if I take the cap off the pop bottle for 10min or an hour then put the cap back on in a short while I have crazy bubbles again for several hours.

This morning, 8:30am, was 10 min off, now it's 1:30pm and I still have crazy bubbles.

Anyone know why or seen similar results?

If not anyone know where I can find Bill Nye?

lipadj46 12-29-2012 06:39 PM

google yeast and aerobic respiration, no science guy needed.

Geniusdudekiran 12-29-2012 07:12 PM

I think that you can find him on some old VHS tapes in my closet from my days where I would sit, fascinated, in front of the non-flatscreen, non-HD TV chanting "Bill! Bill! Bill! Bill!" :hihi:

DarkCobra 12-29-2012 07:16 PM

Yep. If yeast are provided with oxygen, they can convert an equal amount of sugar into *four times* more CO2 (if I recall right), producing no alcohol. :)

The problem is that air is mostly nitrogen. All that inert nitrogen, which is insoluble in water, has to be purged out of the system. Which, depending on your diffusion scheme, creates bubbles that carry away much of your bonus CO2 uselessly to the top of the tank. Or fill a reactor until it burps out nitrogen and CO2. :(

dprais1 12-29-2012 07:34 PM

--facepalm

flc 12-29-2012 09:32 PM

Quote:

Originally Posted by DarkCobra (Post 2132024)
Yep. If yeast are provided with oxygen, they can convert an equal amount of sugar into *four times* more CO2 (if I recall right), producing no alcohol. :)

The problem is that air is mostly nitrogen. All that inert nitrogen, which is insoluble in water, has to be purged out of the system. Which, depending on your diffusion scheme, creates bubbles that carry away much of your bonus CO2 uselessly to the top of the tank. Or fill a reactor until it burps out nitrogen and CO2. :(


And roughly 18x the energy yield from using the Embden Meyerhof Parnas pathway. If the fermentation is being done through the Entner Doudoroff pathway, CO2 production is roughly 1/6 the Krebs Cycle with 1/36th the energy yield. (Due to thermodynamic inefficiency in transmembrane energy transduction, the numbers aren't quite as clean as textbooks state)

Back to the OP's question:
The fizzing effect from shaking is because the solution is "saturated" in CO2 and the kinetic energy you're imparting to the system is just enough to push it over the energy threshold required for a shift in its equilibrium. In other words, you're making CO2 when you shake the bottle.

Unlike O2 (which interacts with water through dipole alignment), CO2 reacts directly with the water: CO2 + H2O --> H2CO3. After a certain amount of time, the reaction making carbonic acid (H2C03) slows until the concentrations of reactants and products reach equilibrium. At equilibrium, the reaction rate in the forward and reverse directions is balanced: CO2 + H2O <--> H2CO3

When you impart energy to the system (heating, shaking, gorgon death ray, etc), you shift that balance. As a result of the reaction being exothermic, the reaction goes faster in reverse than forward, so that the net reaction produces C02 until the relative concentrations reach a new equilibrium state and the rates go back to being in balance: H2C03 --> H2O + C02.

Edit: If you really want to go down the rabbit hole, here's a more complete explanation: http://www.newton.dep.anl.gov/askasc.../chem99661.htm

DarkCobra 12-30-2012 02:15 AM

Wow. Well that puts my explanation to shame. :)

But you might be able to answer a question I have. If there *was* some way to keep the DIY mix aerobic, would it maintain a relatively stable CO2 production, same as we expect from our anaerobic mixes? Or would it instead rise exponentially until all sugar is converted?

dmifflin 12-31-2012 12:32 AM

im going to have to say well done with a side of b.s.. super entertaining btw .

essentially he is right.

dmifflin 12-31-2012 12:46 AM

after further reading i retract my previous b.s. comment. flc you are the biggest nerd i know... praise the nerd.

Diana 12-31-2012 07:34 PM

Yea to flc! Lets name him/her as the 'Bill Nye' of the Planted Tank!
Thank you very much! I have always wondered why stirring the bottle improved the yield, briefly.

ps: my adult son has (lets all sing) "Bill Nye the science guy... Bill! Bill! Bill!" as the ring tone on his phone.


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