# DIY CO2 kit for acid citric and baking soda



## parotet

I've seen on eBay a kit for DIY CO2 based on citric acid and baking soda reaction. I think it doesn't really add  anything interesting compared to the traditional yeast based DIY CO2 (in fact citric acid will be probably more expensive than yeast) and paying that price (20 dollars) I wouldn't expect a good needle valve and the pressure gauge.
But I read something that really surprised me, they explain in their YouTube video and also some users explain in several forums that ''as it is a chemical reaction and not a biological reaction'' you can close the system at night with a valve and the chemical reaction will stop without any risk of over pressure (of course when using the right bottles). This could be the only advantage compared to yeast systems, isn't it?
Is this true? As far as I know, all the reactions are always chemical... The only difference is that in the yeast system, yeast are consuming sugars and producing the chemical reactions for CO2 production. There may be a better explanation for this, I'm sure.


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## parotet

Chemical products are in different bottles, but the valve to stop the reaction is between the last bottle and diffuser...


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## ceg4048

Hi,
	In yeast systems yeast exhale, and when they exhale they exhale CO2. CO2 is the waste product of any cell that burns sugar to make energy. The yeast do not care about night or day. They just keep eating sugar and exhaling. That's why there is no way to stop them at night.

If you are making CO2 by combining two products in a container, then it's easy to control the CO2 production by simply not putting them together. So this sounds reasonable but it's less clear how much CO2 it produces compared to the typical yeast system.

Cheers,


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## parotet

Is there any system to estimate the amount produced for  both systems? Someone has estimated the CO2 produced for example by 2 cups of sugar and the recommended dose of yeast for it?


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## ceg4048

Sorry, I have no idea about the yeast, but it shouldn't be a problem if you know the weights of the ingredients. In any case it's better to use something like Excel or Easycarbo, but they are probably more expensive as well.

Cheers,


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## parotet

Thanks again Clive...


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## jose_j

parotet said:


> Is there any system to estimate the amount produced for both systems? Someone has estimated the CO2 produced for example by 2 cups of sugar and the recommended dose of yeast for it?


 
Hi Jordi,

Yes there is a system to estimate the amount of CO2 produced by both systems. We just have to go back to our 
chemistry lessons at the hight school.

For the Soda + citric acid reaction the balanced equation is:
3 NaHCO3 (soda) + C6H8O7 (citric acid) ==> 3 CO2 (our favourite gas) + C6H5Na3O7 (sodium citrate) + 3 H2O 
(water)

knowing this we can answer how much CO2 can we get from a given amount of soda and citric acid. In the 
balanced equation we have that for every 3 mols of soda combiend with 1 mol of acid we will get 3 mols of 
CO2.

Molecular weights are: 

soda: 84.007 gr/mol
citric acid: 192.124 gr/mol
CO2:44.01 gr/mol

so now we can say that every 252.021 grams of soda mixed with 192.124 grams of citric acid we will get 132.03 
grams of CO2. Now you just have to escale all these amounts by the same factor in order to adapt them to your 
reactives. For example, if you want to set your reactor adding 400 grams of soda, the correcting factor we 
have to apply is 400/252.1= 1.587. So you will need 1.587 x 192.124 = 304.84 grams of citric acid and you 
will get 209.53 grams of CO2.

The same could be done for the yeast reaction, where we do anaerobic fermentation. But in this case is not 
easy to balance the equations as the fermentation gives a mix of impure alcohols and the reaction stops when 
the yeast dies. But anyway, yeast transform sugar into CO2 and ethanol. The balanced equation for the 
reaction in this case is expected to be:

C12H22O11 (sugar) + H2O (water) ---> 4C2H5OH (ethanol) + 4CO2 (our gas)

Molecular weights are:

C12H22O11: 342,2965 g/mol
CO2:44.01 gr/mol

so theoretycally every mol of sugar will produce 4 mols of CO2, that is, every 342,2965 grams of sugar yield 
176.04 grams of CO2 in your yeast reactor.

the soda+citric reaction is fast, if you mix all the reactives you will get all the CO2 at once, this is why in the reactor you mention soda and acid are mixed little by little. The yeast+sugar reaction is slow, cO2 is being released depending in the fungus pupulaion densigy, metabolic rate, temperature, ethanol accumulation, etc ...

Hope this will answer your question. Just double check the calculations, I'm typing faster than I should. I like chemistry but is not my job, so hopefully other members will add their comments and corrections.  

Cheers,

Jose


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## parotet

Thanks Jose for the calculations and your time. Some days go I read in a forum a guy that had serious problems with his little experiment with soda and citric acid... He was using the CO2 set from eBay. Nothing serious but I guess he spent a long and nice weekend cleaning his flat. It seems that the reaction is not so well regulated by the device.

Anyway the best investment I did for the new 60 cm tank has been the pressurized CO2system, no doubt (in the small one I use liquid C). Actually the only thing I regret is not to have bough a better regulator (I have a one stage dual gauged) and a bigger cylinder (I have a 2 kg one)...


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## jose_j

Hi Jordi,

here in our country (Spain) you can easily get a 8Kg or 12Kg if you have a friend that owns a restaurant, pub, bar, etc. Just tell him/her to order an extra gas bottle for the pressurized beer system. Currently I have an 8 Kg one working with an inline atomizer and provides enough CO2 for 8 months in a 300L densely planted tank. The main CON is that this cylinder is bigger in size so you need some space in your cabinet.

Cheers,

Jose


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## parotet

No friends owning bars mate  , should I drink more beers???
There's a LFS here that sells big cylinders for 100-120€ (actually the same cost or just a bit more than 2 kg ones)... how much did you pay for it? The only advantage is that when you run out of gas you can leave it in the shop and take another one, no need to wait for refills, just a few minutes without CO2 in your tank
 (refills: 4€/kg of CO2 more or less, a bit cheaper in FE shops)


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## tim

parotet said:


> No friends owning bars mate  , should I drink more beers???


Always


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## jose_j

parotet said:


> No friends owning bars mate  , should I drink more beers???
> There's a LFS here that sells big cylinders for 100-120€ (actually the same cost or just a bit more than 2 kg ones)... how much did you pay for it? The only advantage is that when you run out of gas you can leave it in the shop and take another one, no need to wait for refills, just a few minutes without CO2 in your tank
> (refills: 4€/kg of CO2 more or less, a bit cheaper in FE shops)


 
Hi Jordi,

I haven't paid for the cylinder, just for the gas charge. The price per Kg is more or less the same you are talking about, so your choice is very good as well.

I have to say that I'm not a great beer drinker, the bar owner that is providing me the gas is the friend of a friend of a friend ... It is always possible to find a link between you and a bar owner


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