Sodium hydroxyde purity

[TheBlob]

Recently I've bought some lye crystals at Home Depot (Canada) expecting some sodium hydroxyde crystals. The problem is: The ''Crystals'' appear to be tiny tiny balls and (correct me if I'm wrong) pure crystalline structures never ever appear in the shape of a ball. I've heard that in Canada, sometimes the name lye is used to refer to Sodium carbonate so I'm pretty confused right now, although I have dissolved some in water and it seems to react with aluminum foil. forming tiny bubbles of flamable gas (hydrogen from what I know), which proves the presence of NaOH.

Is there a way to check for impurities in lye crystals?

[ETCS (Ret)]

Due to the worldwide "war on drugs" it is getting increasingly difficult to find pure Sodium Hydroxide at the retail outlets.

Fortunately, there are some rather easy methods to make your own Caustic Soda from Sodium Bicarbonate (Sodium Hydrogen Carbonate) or Sodium Carbonate which will be sufficienty pure for most applications and considerably more pure than the retail brands.

Pure Lye is usually in the form of flakes; the tiny prills that you have found are probably a mix of Sodium Chloride and Sodium Hydroxide. For cleaning drains pure Lye isn't necessary.

How much Sodium Hydroxide are you in need of? More than it would be convenient to make yourself?

[Silent Freedom]

Lowe’s has a drain opener called "Roebic Crystal Drain Opener" and it advertises right on the bottle that it is 100% lye.

[TheBlob]

Well I would need about maybe 5g so I guess I can make it myself. Though I now need to find another hydroxyde to make some NaOH.

[ChippedHammer]

Its pure, its in a form called 'pearls' which are much like prills.

Sodium hydroxide only comes in two forms, flakes and pearls. Its probably 98-99% pure.

http://www.tradekey.com/ks-caustic-soda-pearls/

[Charles Owlen Picket]

On -=some=- MSDS for technical grade chemicals there exists a CAS level of purity code. This unfortunately, has not been standardized but if it exists for your particular chemical you can find a few items of worth.

Generally, chemical wholesalers like to keep to three gradations (of technical, reagent, & analytical purity). The problem exists with "WHAT" THE MARGIN OF IMPURITY CAN CONTAIN. One issue therefore is: - "would anything be totally inert?" [CAS seems to feel that "inert" is something that can be quantified.] I like it when desiccants are considered inerts, when in fact they are reagents in various other fields, etc.....<sigh>

So far TTBoMK, technical can drop down to as low as 63% labeled purity....That's pretty damn poor; but that what's termed technical. However, mostly it's 93% like in H2SO4 and better. Analytical has to be better than four figures (>99.9999%). This may change as the various EU countries are getting involved in guidelines for precious metals and chemicals.

[Enkidu]

See attachment for details on how to standardize your NaOH soln. This is probably out of your reach, as it requires a primary standard, as Charles was saying, and high precision glass like burrets. However, because you don't need to know EXACTLY what the concentration is, you could just do a couple of rough titrations with muratic acid and that purple cabbage indicator (http://chemistry.about.com/library/weekly/aa012803a.htm).

[TheBlob]

Well I have some 31,45% pure HCl and some litmus papers, I could make a rough titration, pretty easy since they're both strong acid and base, and that would give me an approximate concentration of my NaOH (should have thought of that before).

Only question now is: Usually, does 31,45% pure means weight of the HCl/weight of the solution, or by volume?

[Enkidu]

Weight. Grams HCl / grams solution

[Setharier]

Is it phossible to concentrate 10-15% drain opener NaOH by boiling water out and get 99% crystals? I mean I tried to do so, but actually just got the room extreme NaOH smell and the stuff didn't seem to boil much at all, even placed into sand filled pot over an gas heater.

Btw, does pyrex glass flasks and other ware stand direct heating from ethanol heater nor blue flame "school chem lab heater" - thing?

[russoc4]

Is it phossible to concentrate 10-15% drain opener NaOH by boiling water out and get 99% crystals?

I've never tried, but solid NaOH is very deliquescent (it will absorb water and turn into a solution in a normal atmosphere). So it may take a decent amount of energy to evaporate all of the water.

Btw, does pyrex glass flasks and other ware stand direct heating from ethanol heater nor blue flame "school chem lab heater" - thing?
Pyrex can withstand direct heating. It is one of the qualities of Pyrex to be able to expand/contract quickly without shattering, but it if the flame is hot enough, Pryex will melt like all glasses. The glassware does not need to be engulfed by the flame. It should be raised above the flame and just close enough to be heated.