# baking soda/vinegar CO2 production?



## jschall (Apr 13, 2009)

I've been trying to think of ways to make a baking soda/vinegar CO2 reactor, and my current idea is to take a large sealed container (~2-5 gallons), and pour an entire box of baking soda in, then drip vinegar onto it (a drop every 5-10 seconds should be plenty, easy to adjust.)
Can anyone who's good at chemistry estimate how long something like this would last at one drip of vinegar every 5 seconds?

Baking soda and vinegar are cheap, yeast produces alcohol and probably other potentially harmful byproducts, and dealing with smelly bottles of yeast sucks.


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## rodrigaj (Aug 17, 2008)

I'm not sure sodium acetate, which is a byproduct of your reaction will be any less smelly or bad for your fish. Its a 1:1 mol ratio. So if you produce 1 mol of CO2 you will be producing one mol of sodium acetate.


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## JeffyFunk (Apr 6, 2006)

Some quick napkin math...

Let's suppose you go to the supermarket and buy the largest box of Baking Soda there is (4 lbs according to the Arm & Hammer Baking Soda Website). Assuming Vinegar (Acetic Acid, CH3COOH) is a 5% Solution (i.e. 50 g / L) & The volume of a drop is 0.051 mL (According to Wikipedia - See the last paragraph) ... How long would this box last?

[4 lbs NaHCO3] x [453.59 g NaHCO3 / lb] x [1 mol NaHCO3 / 84.007 g NaHCO3] x 
[1 mol CH3COOH / 1 mol NaHCO3] x [60.05 g / 1 mol CH3COOH] x [ 1 L / 50 g CH3COOH]
x [1000 mL / 1 L] x [1 drop / 0.051 mL] x [5 seconds / 1 drop] x [1 min / 60 seconds] 
x [1 hr / 60 minutes] x [1 day / 24 hours] = *29 days*

More importantly, how much vinegar would this require to run to completion (Stop the calculation chain when you get to L) ? = *26 L = 6.9 gallons*

Of course, you could always reduce the mass of the Baking soda you start with, but then you reduce the time it lasts...

To me, the volume of acid needed would be a problem (not to mention the smell of having to deal w/ that much vinegar... and the cost), but that's just me... (I hope my math is correct ... ) And we haven't even gotten to the issue of whether this would be enough CO2 produced as well

EDIT - I think i might have made a mathematical mistake by not including the density of vinegar in the calculation.. not sure, though... Regardless, the density of the solution would be near 1.00 (the density of d.i. water is defined as 1) and not change the magnitude of the answer(s) by much.


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## jmhart (Nov 13, 2007)

It's certainly an interesting idea. 

I just skimmed through JeffyFunk's math, and it looks dead on. Given the low concentration of vinegar, density isn't going to to effect the math too much.

Vinegar is relatively cheap, but 7 gal a month will certainly add up. 4 lbs of baking soda will also definitely not be cheap. That alone makes the whole thing cost prohibitive.-------scratch that, just looked it up

12 lbs of Arm and Hammer off Amazon for ~$11 plus shipping. That's a 3 month supply.

6 gal of acetic acid wouldn't be awful to deal with. Sure, to some it would stink, but you could put it in a sealed chamber with a pump(low flow of course) and never have to smell it again. CO2 levels could be controlled by speed of the drip. You'd end up with a lot of waste for sure, which won't be pleasant to deal with. 


It's still much more expensive than DIY, but if money's not the issue then I see a possibility here....but then again, if money's not the issue, pressurized is the way to go for maximum ease of use. 

You could even look into some higher strength acetic acid. May or may not be a lot more expensive per % acetic acid, so it might get pricey, but it would cut down on the volume required.


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