How to Make Lye From Baking Soda and Hydrogen Peroxide

Intro: How to Make Lye From Baking Soda and Hydrogen Peroxide

I made this project because it took me WAY too long to find out how to make lye from stuff I personally had lying around the house. This is stuff others do not (the chemicals came from a chemistry kit). It took me quite a bit of digging to find out how to make lye from household materials that everyone has in their house (My two sources were a chemistry book from 1936 and a few forums [trust me this works, I asked my chemistry teacher and tested the lye]), and I want to share that so others don't have to do that digging. Also, I am writing this so I can enter it in the contest (:

There are lots of projects you can do with lye, such as make soap, magnetic nanoparticles, sodium metal, and many others. It is a caustic chemical though, so BE CAREFUL

STEP 1: Equipment and Chemicals

To make lye you will absolutely need:

• Container (preferably glass)
• Hydrogen peroxide (You can buy this in the pharmacy at most stores. It's usually sold as "Hydrogen Peroxide" XD in a brown bottle. You probably already have some in your first aid kit)
• Baking soda (Sold as "Baking Soda")
• Something that can deliver gentle heat, like a desk lamp. See the picture if you have no idea what I am talking about.
• Something you can measure stuff with (either by volume or weight. If it is by weight, make sure your scale can measure grams. If it is by volume, make sure your measuring cup can measure milliliters)
• Patience
• Common sense (seriously)
• Something to stir with

These are optional things that will make it easier:

• Another container (the bigger the area the better. So you want it large. It does not necessarily have to be deep) that you are okay with potentially ruining, and can let it sit for a while
• Something to store your lye in (Once again, preferably glass, and it DEFINITELY needs a screw on top)

Also for safety (probably necessary) :

• Gloves (rubber, not cloth)
• Goggles (the splash guarding ones, look at the picture)

STEP 2: Measure Out the Ingredients

It's time to use some math. Find out the percent of your hydrogen peroxide. Then figure out how many milliliters you want to use. Multiply those two numbers together (remember that percents are the percentage/100, so 3% is 0.03), and than multiply that by 7.25 to find the amount of grams of baking soda you need. To find out how many milliliters of baking soda, divide grams of baking soda by 2.2. You may need to do a bit of converting to get teaspoons of baking soda.

STEP 3: Mix the Ingredients and Warm It Up.

After you are done measuring out the chemicals, put them in your container (you don't need to stir but you can). Put the container under a lamp like in the 3rd picture, so the bulb is about 3 inches inches away from the liquid. Make sure the bulb isn't touching the liquid. If you are having trouble getting the lamp to balance, place something heavy on the base (if you look on the right of the 3rd picture you will see my baking soda box). After a little bit, it should start to bubble. Check on it every once in a while to make sure it is not bubbling over or getting too hot (if it hurts to touch it, it is too hot). If it is too hot, take the lamp away for a bit, and then put it back. Once it has COMPLETELY STOPPED BUBBLING (make sure little bubbles aren't still being produced. Also the baking soda may not have completely dissolved), the first reaction is definitely over. Wait at least 30 minutes before you take away the lamp, just to be safe.

STEP 4: Get the Dry Lye From the Solution

After it has stopped bubbling, it is time to get the lye crystals(more like lye hunk). Pour the liquid, and preferably only the liquid, in the original container into the second one if you have one. If you don't, just leave it as it is. Either way, find a place to put it where it won't be disturbed for a while and is out of children's reach. This will take a while, and the flatter the container the shorter it will take. Wait until the crystals are white, like in the 4th and 5th pictures.

STEP 5: While You Are Waiting....

Here is the science behind this. There are actually two chemical reactions happening. One of them is

2NaHCO₃ + H₂O₂ → NA₂O₂+ 2H₂O + 2CO₂ (2 baking sodas + hydrogen peroxide →sodium peroxide + 2 waters + 2 carbon dioxides)

After that reaction this one happens:
Na₂O₂ + H₂O → 2NaOH + (O)↑ ( sodium peroxide + water → 2 sodium hydroxides + a single oxygen atom )

Which thus creates lye and water (after the gasses have bubbled out). Pretty neat, right?

STEP 6: Store It.

Store the lye somewhere were children can't get it. Keep away from oxidizers. I am not responsible for any damage caused during or because of the products of this experiment. Keep in mind lye is also a very, very strong base which means it will burn you if you are not careful.

You can do some interesting stuff with lye. Since it is extremely basic (the opposite of acidic), you can do the purple cabbage experiment with it. You can also use it to make soap, magnetic nanoparticles, sodium (be careful), and many others. Have fun, but please be safe.

Comments

[ronallens777]

interesting.. spent way too long working this out for my own needs... i dont see the point of running it into crystals unless you really need them... took me awhile to work it out to a 50% solution for an herbicide or soap as that is what is most commonly used. I am not so organized so I just copy and paste my notes and calculations.::

hydrogen peroxide pure .... 1.4425 gram per cubic centimeter
BAKING SODA ........ 28.340695 gram per oz
2.2 grams per cubic centimeter
One mole of a substance is equal to 6.022 × 10²³ units of that substance
(in moles)2 units of baking soda plus 1 hydrogen peroxide = 1 unit of hydroxide
2(84g)=168g + 34.0146g (@3%=593.81027g(w/32.3 mole water)) = 39.997g
559.79567g water
20.079 oz
solution 50% 500mg to cc
formula per grams to millitiers
ccm = ml
1 oz = 28.3495g
1 lb = 453.592g
1 gal = 3628.736g
water 0.9998395 g/ml
3% peroxide 1.00g/cm
make 1 lb, x 11.3407
1905.2376g + 6734.2241g = 1 lb/212.954 ml
67.2oz (4.2 lbs) 227.70oz(6.33 qts)
peroxide is %.... 100g of peroxide is 3g of pure
peroxide pure X 7.25 = BS in grams
BS in grams /2.2 = BS in milliliter
peroxide 3% is
3 ml peroxide pure + 97 ml water
1 oz = 29.5735ml
one mole of sodium hydroxide has a mass of 39.997 g
Sodium hydroxide weighs 2.13 gram per cubic centimeter
50% solution 100ml to 100g 212.954 ml(hy) + 454 ml(water) = 667 ml solution
...................................................
end result 2 hydroxides and 1 O gas... 2 bs to 1 hydroxide
Baking soda is sodium bicarbonate*, NaCO2OH: has a molar mass of 84 g/mole
So hydrogen peroxide has a molecular weight of 34.0146 grams per mole
The atomic mass of hydrogen is 1.0078 and the atomic mass of oxygen is 15.999, so the mass of a mole of water is 2 x 1.0078 + 15.999. Therefore, a mole of water, or 6.022 x 1023 molecules, weighs 18.0146 grams
97/3
1747.4162+34.0146= 1781.4308g/3 =593.81027g is 1 mole of h2o2

It's time to use some math. Find out the percent of your hydrogen peroxide. Then figure out how many milliliters you want to use. Multiply those two numbers together (remember that percents are the percentage/100, so 3% is 0.03), and than multiply that by 7.25 to find the amount of grams of baking soda you need. To find out how many milliliters of baking soda, divide grams of baking soda by 2.2. You may need to do a bit of converting to get teaspoons of baking soda.
peroxide 3%
ml x .03 =h2o2
h2o2 x 7,25 = =bs
bs g /2.2 - ml

[sarahg1234]

Hello, i was wondering if i could use the liquid form directly to make my soap? Or do i need to cure/dry it until it forms crystals and after desolve it in water? To be able to obtain the lye solution
Thank you

[ronallens777]

i worked out what i needed to reduce the whole process to get to a 50% solution if you are interested... its in the comment i am leaving on the forum

[aolivier747]

It depends... I haven't tried this yet, but i guess you could if 1: there is no baking soda left at the bottom and 2: the hydrogen peroxide has completely reacted/decayed. Technically if you filter the liquid and let it exposed to sunlight for a while to remove the H2O2 it should work, but i suggest getting the crystals just to be safe.

[phyzome]

I didn't see any straightforward, grams-based recipe and I couldn't puzzle out the percents-and-milliliters instructions. Here's what I think is correct based on the chemical equations and molar masses: To make 1.0 g NaOH I think you need 4.2 g NaHCO3 and 28 g 3% H2O2. I haven't tried this, though. :-)

But you probably want a little excess H2O2 to ensure all of the baking soda is consumed; the remaining H2O2 should decompose and evaporate off by the time the lye is solid and dry.

----

Math for the above, just ignore unless you want to check my work:

NaOH is 39.9971 g/mol
1 g NaOH: 1/39.9971 = 0.025001813 mol NaOH

Need 2x of NaHCO3 (0.050003626 mol) and 1x of H2O2 (0.025001813 mol)

NaHCO3 is 84.0066 g/mol: 84.0066×0.050003626 = 4.200634608 g
H2O2 34.0147 g/mol: 34.0147×0.025001813 = 0.850429169 g

So for 3% H2O2, you need 0.850429169/0.03 = 28.347638955 g

[kanyeaustin]

Leach wood ash with water. By far way easier and cheaper. Burn wood, rinse ash, evaporate = lye

[aolivier747]

This makes potassium carbonate (potash), not sodium hydroxide. Both can be used for soap though

[Ubya]

this could be ok if you need a few grams, but if you need more than that it's going to be quite expensive. electrolysis of sodium chloride is the best choice (after buying it of course)

[klrsolid]

Is it true that the method using sodium chloride electrolysis leaves CHlORINE in the final product?

[samuelx3]

yea, u can use sodium carbonate though

[mrmolamola]

I know, but electrolysis of sodium chloride requires to setup an electrolysis container, which is kind of a pain, and you need pipes which not everyone has.

[IS2Chemistry]

Hello, can you please provide more details about your 1936 book? And how does the heat from the lamp affects the reactions? Thank you.

[samuelx3]

a general rule of thumb is 10° C change in temp means 2 times slower or faster or somethign like that. heating it up makes reaction go faster

[IS2Chemistry]

Thanks!

[chouchou.martin007]

When I did this experiment I got something different for the 2nd RXN:
Na₂O₂ + 2H₂O → 2NaOH + H₂O₂. (because why are we suddenly down a water in the next reaction?)

If this equation is right you may want to leave the crystals in the sunlight to breakup the hydrogen peroxide.

Also when trying to find out the amount of baking soda (grams) to use it may be more accurate to use: [ml of H₂O₂ x % of H₂O₂ x 7.103]

I redid and balanced this equation, as well as found out the measurements for a 3% solution of hydrogen peroxide and aligned the moles in a ratio to find out the amount of 7.103.

Resources I used:
https://www.wolframalpha.com/
https://www.webqc.org/balance.php

[stfu1708]

In practice, a balanced equation is not necessarily an accurate one. Without adequate information about the physical reality of a reaction, one cannot determine which of multiple possible configurations will result, if a reaction takes place at all.
The actual reaction:
2Na₂O₂ + 4H₂O → 4NaOH + 2H₂O + O₂
As he said, after the oxygen gas bubbles out of the solution, you are left with lye and water.
Edit: At the ratios specified above, you would indeed be left with a single oxygen atom as the post indicates. In actuality, however, oxygen is too reactive to exist as a single oxygen atom, and will readily form O₂ as the reaction occurs. I neglected this detail when I originally wrote this, so I have updated the equation accordingly, doubling everything to balance the O₂, to more accurately reflect the nature of the reaction.
P.S. Tip to the poster, instead of saying "basic (the opposite of acidic)" you could just say "alkaline." Much more concise. :)

[samuelx3]

Could I also use a incubator for this reaction? (You know the one for chicken eggs)

[samuelx3]

Could I use a very hot water bath as a heat source?

[sosouix]

I tried this with a crock pot on low for lack of a heat lamp (100 ml of hydrogen peroxide 3% same as indicated, and 25 grams of baking soda), the water bi-product evaporated quite quickly too and left only the crusted lye.

[David Hoskins]

After the reaction stops can you transfer it to a plate but keep the heat lamp on it to speed up the drying process?

Also I thought this was the process you use to make Sodium Peroxide, the stuff they sell as "Oxi-Clean"? I know the ratios are very different so maybe Oxi-Clean has a little Sodium Hydroxide mixed in as well?