Check my math re: lye solution

[BCRider]

Of course true purists mix scotch with ice and coca-cola in quantities of each that is pure art in the making.

TROLL ALERT! There's a TROLL in the group! ! ! !

There's a special place in Hell for anyone that mixes cola with any of my single malts.......

[lakeside53]

same for tap water in mine!

[Bob Engelhardt]

I use lye as a paint stripper and keep a quantity around to be able to dunk parts in it. My problem is not knowing the extent of exhaustion of the lye. I don't want to throw out lye that is still potent, but I don't want to waste my time with exhausted lye. "Try and see" is not very effective because paint varies in its susceptibility to lye.

So, is there a convenient way to measure its strength, other than titration, or pH strips? They are no good because the lye becomes contaminated with paint coloring and obscures the strip color.

Thanks,
Bob

[boslab]

A Baume hydrometer was used when I checked the conc of the caustic tanks years ago in an Ali works, I remember vaguely the figures but not well enough to commit to writing, % conc etc, I have seen articles on the web giving the rel density an hydrometer readings you get.
Also bear in mind the temp of your etch tank is relevant, warm is faster, ours were boiling, nasty, extraction needed but we were cleaning the Ali spew off extrusion dies, it eats it away nicely.
Spent bath was neutralised with acid, in thier case whatever was cheap!, acids aren't that cheap.
Again usual safety applies
I have related it before but worth rewriting, had a delivery of sulphuric, the tanker coupled up to a sodium hypochlorite fill point (should have been a different size hose coupler, a new hose on the lorry had resulted in the. Wrong coupler being fitted) the driver pumped a couple of tons of acid into a half full hyper chlorite tank, he heared noises from the water treatment plant building before he realised, He ran just before the side of the building blew out, lucky he would have been poached with acid.
Mark
http://www.handymath.com/cgi-bin/spc...i?submit=Entry

[Mike Amick]

The molarity is really not that important.

ahhhh come on Jerry !!! you throw that 5 dollar word out there .. and when I look it up ... I
don't even understand the definition !!!!

quote:
Image result for molarity A dash is usually used when you write the word 'molar.' And
never forget this: replace the M with mol/L when you do calculations. The M is the symbol
for molarity, the mol/L is the unit used in calculations. Example #2: Suppose you had 2.00 moles
of solute dissolved into 1.00 L of solution.

????

[RichR]

ahhhh come on Jerry !!! you throw that 5 dollar word out there .. and when I look it up ... I
don't even understand the definition !!!!

quote:
Image result for molarity A dash is usually used when you write the word 'molar.' And
never forget this: replace the M with mol/L when you do calculations. The M is the symbol
for molarity, the mol/L is the unit used in calculations. Example #2: Suppose you had 2.00 moles
of solute dissolved into 1.00 L of solution.

????

If you're suffering from molarity, you might need to see a dentist.

[Dan_the_Chemist]

So, is there a convenient way to measure its strength, other than titration, or pH strips? They are no good because the lye becomes contaminated with paint coloring and obscures the strip color.
Bob

Aquarium pH meter, $8 Free Shipping from China on eBay. Probably barely more accurate then sticking your finger in and tasting it, but a lot easier on your finger and tongue.

[Norman Bain]

Look ... not to derail the thread; which is a topic not much discussed previously and which I am following with interest. But there is another method of working out the balance of fluids/materials being mixed.

That method is sound. Yous will have noticed that when you put ice in a good glass; add scotch; then proceed to add coca-cola that there is a tinkle. That tinkle (that sound to the trained ear) is very pleasing, plus a side effect is that it lets the trained participant gauge to perfection the amount of coca-cola being added.

[Bob Engelhardt]

Aquarium pH meter, $8 Free Shipping from China on eBay. Probably barely more accurate then sticking your finger in and tasting it, but a lot easier on your finger and tongue.

Perfect! One's on its way. Accurate would be nice, but repeatable is plenty good enough (I can calibrate to known solutions). Thanks

[J Tiers]

ahhhh come on Jerry !!! you throw that 5 dollar word out there .. and when I look it up ... I
don't even understand the definition !!!!
......

But dat's what da OP wuz talkin 'bout. I just figured I'd follow along.....

Besides, I had been just talking chemistry with my father, who's been a chemist for 70+ years.... it rubbed off on me.

Anyhow , that's only a 3 buck word. It doesn't have enough letters to charge full pop for it.

[MattiJ]

Aquarium pH meter, $8 Free Shipping from China on eBay. Probably barely more accurate then sticking your finger in and tasting it, but a lot easier on your finger and tongue.

Isn't pH meter going to show about same value for 1% and 20% natrium hydroxide solution?

[Horst]

Thank you all for your answers. Here is the genesis of the question.

• Decide to build lye tank for ongoing/repetitive cleaning of enameled and cast iron stove parts
• Unable to eliminate very tiny leaks in plastic tank (12"x24"x4") as determined by placing full tank on paper towels.
• Decide to seal rather than invest in proper plastic welding setup (used soldering iron)
• Look up compatibility of silicone with lye
• Compatibility based on % solution of lye (20% - 50% - 80%)

The problem arose in trying to determine what these percentages really meant (silicone is good @ 20%; less so @ 80%). That’s where I got tangled up with molarity. What was giving me doubt was that 3# per gallon is a stronger solution than I have used in the past and how could it be that it yielded only a 9% solution. According to that math I would need to add 30# per gallon for a 90% solution and that did not seem right (even possible?).

If we are talking weight/weight then adding 2# per gallon yields about 25%. This is about as strong as I have been comfortable with in the past and is strong enough to be effective.

So the question I still have is how does that compare with what I am seeing in the chemical compatibility chart? I guess the real question is “can I safely seal my lye tank with silicone?”

Now that I have the attention of chemists I would like to know if a stronger solution would be more effective in removing burned on food and grease without damaging the enamel. At 2# per gallon it takes a day or three to work.

[chemist6.02e23]

Thank you all for your answers. Here is the genesis of the question.

•Decide to build lye tank for ongoing/repetitive cleaning of enameled and cast iron stove parts
•Unable to eliminate very tiny leaks in plastic tank (12"x24"x4") as determined by placing full tank on paper towels.
•Decide to seal rather than invest in proper plastic welding setup (used soldering iron)
•Look up compatibility of silicone with lye
•Compatibility based on % solution of lye (20% - 50% - 80%)

The problem arose in trying to determine what these percentages really meant (silicone is good @ 20%; less so @ 80%). That’s where I got tangled up with molarity. What was giving me doubt was that 3# per gallon is a stronger solution than I have used in the past and how could it be that it yielded only a 9% solution. According to that math I would need to add 30# per gallon for a 90% solution and that did not seem right (even possible?).

If we are talking weight/weight then adding 2# per gallon yields about 25%. This is about as strong as I have been comfortable with in the past and is strong enough to be effective.

So the question I still have is how does that compare with what I am seeing in the chemical compatibility chart? I guess the real question is “can I safely seal my lye tank with silicone?”

Now that I have the attention of chemists I would like to know if a stronger solution would be more effective in removing burned on food and grease without damaging the enamel. At 2# per gallon it takes a day or three to work.

I am more concerned about the compatibility of PVC with strong base. I think you will be better off with a five gallon pickle bucket (or Home Depot orange bucket) than PVC. PVC will react with base and become embrittled. I would not want a tank of strong base to fail suddenly.


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[Bob Engelhardt]

Aquarium pH meter, $8 Free Shipping from China on eBay. Probably barely more accurate then sticking your finger in and tasting it, but a lot easier on your finger and tongue.

Perfect! One's on its way. Accurate would be nice, but repeatable is plenty good enough (I can calibrate to known solutions). Thanks

Decided to try it out today and read the instructions (!). To calibrate, they supply powders that are to be dissolved in deionized water. Well, the DI water will cost more than the meter!

How badly would the calibration be compromised by using distilled water? Or is there some other water that isn't $20 a gallon that I can use?

Thanks,
Bob