Been a lurker for a bit and have been reading all the great info here. I had a question I was hoping someone could help with: does lye go bad? I picked ups new bottle of sodium hydroxide at the hardware store today and put 150g into two seperate glass containers of 250cc h2o expecting an exothermic reaction.... I have been stirring for roughly 1/2 hr and still have undisolved crystals in the bottom of both with no noticeable heat or visible reaction. I don't want to use this if it's going to ruin any experiments, what are your thoughts fellow Nexians?

It's been over an hour sitting in a gallon jug with periodic shaking... Still have crystals in the bottom with no exothermic reaction. My guess is they sat at the he store long enough it must have reacted with the air. Label says 100%!?! no clumps; guess I'll seek another source.

Perhaps there's a measurement error and water has reached its maximum saturation point ?

Try adding adding about 200cc of water.

I used a digital scale to measure weight in grams and then slowly poured it into 250ml water in a glass measuring cup. No reaction noted at any point in the lye addition. I started slow and when nothing was happening I just dumped in the rest.

Do you think it's saturated? I would think I'd have noticed some reaction when I dumped it in .... I'll add some water and see what happens

If you never noticed any heat then it is certainly not saturated with lye. I use a HDPE jug and I dump 100g of lye into 600ml water, the jug gets too hot to hold, feels close to boiling point and its nowhere near saturation.

If the problem persists, filter the aqueous "lye" solution out and leave the precipitates behind. Take around 5-10 mL of your solution and put it in a separate container or test tube. Dip a small piece of aluminum into your solution and expect an exothermic reaction and hydrogen gas.

You should be able to dissolve about 109g NaOH in 100mL H2O at 20ºC. It should dissolve easily in the amount of water you used, I would also expect heat to be released.

Quite what has happened here though I don’t know!

I returned it and utilized a different Product and things went as expected. Still not sure the story on the bad lye