lye from washing soda and lime

[lorentz5]

SWIM has searched and can't find mention of this simple process on the Nexus. The objective is to produce small amounts (less than 1 pound) of sodium hydroxide without buying it and arousing suspicion. Lime and washing soda are relatively cheap and most Nexians have them already. Obviously, buying lye is cheaper, but in small quantities, it doesn't make a big difference.

Sodium Hydroxide from Lime and Washing soda​

Sodium hydroxide may be formed by the metathesis reaction between calcium hydroxide(also known as lime) and sodium carbonate [Chemistry Precision and Design.Verne Biddle, Gregory Parker.A Beka Book, Inc.]

Ca(OH)2 + Na2CO3 → CaCO3 + 2 NaOH​

Solubility of CaCO3 in water is 0.015g/L at 25C
Solubility of NaOH in water is 1110g/L at 25C

Example: In preparation for the BLAB (250g NaOH), 232g lime is added to 331g washing soda in water. Washing soda is very soluble in water, but lime isn't. SWIM doesn't know how long this reaction would take to complete or how much water is ideal, but he imagines heat would facilitate the reaction. CaCO3 will precipitate and can be filtered off. The filtrate can be evaporated to yield 250g NaOH crystals.

What do you guys think? Is this a good idea for small-scale extractions?

 

[Gir]

SWIM doesn't know how long this reaction would take to complete or how much water is ideal, but he imagines heat would facilitate the reaction.

What do you guys think? Is this a good idea for small-scale extractions?

Needs more research.. might be good but it sounds dangerous.. What kind of reaction will occur? How are you going to filter a caustic material safely? the calcium carbonate could be dangerous to handle.. the entire thing could be a caustic nightmare..



or it could be a beautifully simple solution to the watched chemical dilemma

 

[lorentz5]

Needs more research.. might be good but it sounds dangerous..

Indeed. This was a very hard task for SWIM because he is not good at chemistry and there's little documentation on this reaction.

What kind of reaction will occur?

A quiet one. SWIM didn't notice his container getting warmer.

How are you going to filter a caustic material safely?

SWIM did it the first time with a lab filter and a his largest buchner funnel. He noticed that his filter had very light yellow stains after it dried. He thinks that filtering is actually unecessary. In his second test, SWIM added 37g lime to 53g washing soda, added 3L water, mixed for 10min. The solids completely settled to the bottom after a couple minutes and SWIM could see through the water to the solids (the water was very clear). He pippeted it out, and the solution tested deep blue with litmus. SWIM is not sure if this was caused by sodium hydroxide or sodium carbonate. SWIM spilled some of the solution on paper by accident and it stained dirty yellow, characteristic of sodium hydroxide. He is evaporating the solution at the moment so he can do more tests later.

the calcium carbonate could be dangerous to handle.

It couldn't. Calcium carbonate is very safe to handle. If gloves and goggles are used, then no problems should occur, given that the worst that can happen are splashes and spillages, no fumes. SWIM sees one problem with the reaction, and that is due to the insolubility of lime. If one reactant is soluble in water, and the other only slightly, will the reaction proceed to completion given enough time?

 

[fraterS.O.L.]

lime is actually more soluble in water the colder the water gets. one of those things nature got ass backward i guess. dont know if that helps but thats what ive read

 

[fraterS.O.L.]

Well folks this thread got me thinking. Even though I personally am not picky about food-safeness, it may interest those who are that theres a possibility of achieving NaOH without going down the drain-cleaner isle. I just took 100g each of lime and sodium carb, mixed with just over a cup of water, in different containers and put em together. I don't think the solubility of the lime will be a problem as it immediately started heating up. I will let you know how much precipitates out so we can have an idea how much NaOH was produced. (p.s. i know its the real deal as i had the pleasure of getting a little on bare skin)