Sciencemadness Discussion Board - Hydrochloric acid from citric acid and sodium chloride?

Hydrochloric acid from citric acid and sodium chloride?

Vylletra Heart - 14-2-2018 at 07:15

I know this may sound crazy but I do believe there isn't an obvious issue with this working in theory. Here it goes.

In the well known displacement reaction between sulfuric acid and sodium chloride, hydrogen chloride is generated in situ which can be distilled off, driving the equilibrium forwards towards the formation of sodium bisulfate. This also seems to work for sodium bisulfate and sodium chloride, but only if the reaction takes place dry or in limited amounts of water, where instead of distilling azeotropic HCl, the said gas is bubbled into water instead.

By adapting this idea to citric acid, I don't see an issue as to why a similar reaction would not take place as well. The issue I'm having with this method seems to be that if I tried distilling the azeotropic acid from a typical distillation setup, the precipitated salt caused by the evaporation of water renders my boiling chips useless and severe bumping occurs. On the other hand, heating the 2 reactants suspended in a small amount of water in a sealed conical flask leading into water only causes a brown product to form, and smelly fumes(it does not sting when breathed in though) which seems to make my rubber tubing sticky. Considering that I use an induction cooker that has a fixed temperature heating system, I've made sure that the temperature of the reaction mixture is just slightly above the boiling point of water, although citric acid may have started to decompose even 50 Celcius below it's projected decomposition temperature of roughly 150 Celcius.

You might be asking why I bother using citric acid, well in my country, sulfuric acid and sodium bisulfate are chemicals that are not over the counter, and even then scientific companies either do not seem to be willing to sell to individuals or are few at best. Such is the life under a restrictive Singaporean government. The only non-volatile cheap acid I currently have access to is citric acid from the baking store. I'm still trying my best to come up with other reactions that might be theoretically feasible, but I'm getting really annoyed by the fact that I have to work so hard just to make such a simple and cheap acid that is so readily available in the US. I've also tried distilling from a toilet cleaner which is HCl-based, but it seems to make my glassware cloudy which does not seem to come off even with hot acidic chromate washing or methyl ethyl ketone, so I'm keeping that as a last resort.

I would really like to hear if there is some problem to my method (because I'm planning to use it to make glacial acetic acid by replacing sodium chloride with anhydrous sodium acetate) or if there might be another economically viable method using stuff from the supermarket.

Thanks for reading!

Chemi Pharma - 14-2-2018 at 07:31

I believe you'd better try sodium chloride and phosphoric acid, obeying the chemical law that's say a fixed acid can deslocate a volatile acid, like HCl.

If it's hard for you to get even phosphoric acid to get HCl, then, I suggest you to concentrate vinegar (+-5% ACETIC ACID), as your goal is to obtain quite pure glacial acetic acid.

See more details how to concentrate vinegar and to obtain glacial acetic acid here: https://www.sciencemadness.org/whisper/viewthread.php?tid=80...

Bert - 14-2-2018 at 08:46

What is the penalty for setting up a home chemistry lab in a country that fines people $100,000 for importing chewing gum?

Quote:

I've also tried distilling from a toilet cleaner which is HCl-based, but it seems to make my glassware cloudy which does not seem to come off even with hot acidic chromate washing or methyl ethyl ketone

Out of curiosity, are you working in borosilicate glass, or ordinary glass?

Could you post a link to SDS or MSDS of the toilet bowl cleaner you used, wondering what ELSE is in your HCl based toilet bowl cleaner?

As far as things from grocery stores, garden stores, hardware stores, etc. "over the counter" and home acid production, do you have available any of these?

Battery electrolyte (30% Sulfuric acid!), should be available at auto stores or other stores selling Lead acid batteries. They do have automobiles in Singapore, which implies batteries?

Concrete etching solutions (hardware store, builder's supply)

Sodium metabisulphite (used in wine making)

Hydrogen peroxide (drugstore, hair salon, hydroponic store)

Copper sulphate (algaecide, tree root killer for drain pipes getting wrecked by nearby trees, Bordeaux or Burgundy mixtures for controlling insects or fungus on fruit crops, KILLING MALARIAL MOSQUITO LARVAE- Singapore has mosquitos and is tropical?)

Ferrous sulphate ("Green vitriol" or "copperas", Iron fertilizer and soil acidifier, from garden store or hardware store)

Sodium or Potassium nitrate (used to preserve color in meats, grocery store, pharmacy, food supply company)

Sulfur (dusting Sulfur, used to control fungus on trees)

Vinegar

[Edited on 14-2-2018 by Bert]

[Edited on 14-2-2018 by Bert]

Texium - 14-2-2018 at 10:14

My gut feeling is that it wouldn't work, but why not try it? Wikipedia says that citric acid will melt at 150C and decompose at 175C, so ideally you'd keep it between those temperatures. You'd also want to use a greater than 1:1 molar ratio of citric acid to your salt, cause even though it's a triprotic acid, the second and third protons are even less acidic than the first.

Vylletra Heart - 15-2-2018 at 05:21

Quote: Originally posted by Bert

What is the penalty for setting up a home chemistry lab in a country that fines people $100,000 for importing chewing gum?

Quote:

I work with a distillation equipment bought through Amazon, which was touted to be borosilicate glass. I've used it to distill sulfuric acid from CuSO₄ electrolysis.

As for the toilet cleaner, it is a home brand from the supermarket and doesn't seem to have another other information other than wetting agent. I've checked the supermarket's website as well. I'm sorry if I'm not looking for a large variety of chemicals because I don't come up with many unorthodox theories to produce HCl.

There is a hydroponics store that sells KH₂PO₄, and according to the Hasselbalch equation, at pH 7 roughly 60% of H₂PO₄^- would be dissociated(this is what I would assume would be the source of free H₃O⁺ to react with Cl^-. This is also assuming that if the reaction mixture is just dry reagents mixed together, where HCl would be produced until the mixture becomes neutral(I might be wrong anyway).

Now I know I've made sulfuric acid already and I can use that to make HCl, but the issue is that the copper sulfate pentahydrate is rather expensive for the yield, S$30 for roughly 100ml of azeotropic concentrated sulfuric acid on the basis that the salt is pure in my theoretical calculations. Pharmaceutical 3% hydrogen peroxide is also rather expensive, and the hydroponics store doesn't sell this though. I do have calcium nitrate, sulfur and vinegar. I might check out an auto store soon, may I know what is the usual cost in your country for battery acid, and if the price varies widely internationally?

Regarding your other listed chemicals, I have not checked them out yet because I don't see how they can be precursors to HCl. Would you mind elaborating on the reaction procedure for them? I have tried bubbling chlorine gas into an aqueous suspension of sulfur, but I don't think I'm properly equipped , and the reaction doesn't seem to proceed.

[Edited on 15-2-2018 by Vylletra Heart]

Bert - 15-2-2018 at 05:55

You are trying to jump to the second synthesis without doing the first- Sulfuric acid.

Hydrochloric acid from sulfuric acid and salt. Nitric acid from an alkali nitrate and sulfuric acid.

Battery acid, it has been a few years, but last time, midwestern USA- $25.00 US for 5 gallons of 30% sulfuric acid, which boiled down, produced around 1.5 gallons of somewhere near 84% estimated from density. If you are in a city, the huge clouds of white smoke might be a problem.

The rest of the materials are all capable of producing sulfuric acid. A few minutes with google and this site would tell you how.

RawWork - 15-2-2018 at 06:39

Interesting topic. That's what I wonder too, can reverse reactions happen?
We all know that hydrochloric acid or sulfuric acid will react with citrate to produce citric acid and chloride or sulfate.
We know that sulfuric acid will displace nitrate to make nitric acid and sulfate...
But that is probably only under standard or close to standard conditions.

Found in Handbook of Inorganic Chemicals this:
"Thermal reduction processes are not being practiced anywhere in the world at present for large-scale production of sodium. Such methods, however, can be conveniently adapted for laboratory preparation of metallic sodium. Sodium can be prepared by thermal reduction of its hydroxide, carbonate, or chloride at elevated temperatures. These salts are heated with carbon, calcium carbide, iron carbide, ferrosilicon, or other reducing agents at temperatures above 800°C under vacuum:
6NaOH + 2C → 2Na + 2Na 2 CO 3 + 3H 2
Na 2 CO 3 + 2C → 2Na + 3CO
2NaCl + CaC 2 → 2Na + CaCl 2 + 2C"

I believe all reverse reactions can happen. All reactions are relative. Under specific conditions reverse reaction happens.

Bert - 15-2-2018 at 07:19

Yes. Reactions have equilibriums, depending on circumstances, they can be pushed one way or the other.

Unless products LEAVE (acid distilled off as a gas?) or otherwise becomes UNAVAILABLE (turns into an insoluble compound and no longer can participate in a wet reaction?).

People here spend a lot of time thinking about this and EXPERIMENTING, figuring out how to get the results skewed in the direction of a desired product.

woelen - 15-2-2018 at 07:26

You indeed can make strong acids from weaker acids and salts if in some way you can either remove the acid from the mix, or the resulting salt. This works for the weaker phosphoric acid and NaCl. The strong acid HCl can be driven off as gas and NaH2PO4 remains behind.

With citric acid the situation is less favourable for making HCl. Citric acid is a really weak acid, so in equilibrium you will only have very very dilute H(+) and hence making HCl from that is difficult. Another issue is that either you have a lot of water in the mix to allow formation of HCl, or you need strong heating to make some HCl. In the former case, because of the very low concentration of HCl and the azeotropic nature of HCl/water mixes, I expect you to drive off only water. In the latter case you probably will decompose the citric acid before any decent amount of HCl can be formed.

The reason why it works quite well with phosphoric acid is that HCl is only sparingly soluble in H3PO4 of 90% or so. The acid also is much stronger than citric acid (at least the first acidic hydrogen is) and this allows HCl to be driven off. A similar thing is true for NaHSO4.H2O, allowing humid HCl to be driven off, good enough to make decently concentrated hydrochloric acid. The anhydrous NaHSO4 works worse, you need very strong heating of the salt mix before you get any HCl.

So, altogether, I am not very optimistic about making practical amounts of HCl from citric acid and NaCl, useful for experimenting. You will get trace amounts of HCl in water, but if you can get better than 0.1% HCl then I think that you already did a very good job.