Easy/Cheap ways to determine what a substance is

I am a complete laymen when it comes to chemistry, but I’d like to know what I can do find out what this stuff is.

It was in my tap water, it is a very fine soft white powder like flour but it sparkles in the light like sand.

It would seem to me it could possibly be a mineral (or at least it should be). If it is in the tap water, no matter what it is it should be organic correct?

Would it be easier to first determine if it is organic or not then work from their?

Any help would be appreciated.


Given your layman chemistry knowledge and lack of equipment, you aren’t going to be able to positively identify it. There are some simple tests you can perform with supplies at home to maybe narrow it down, but it won’t give you a firm answer. See here (PDF) for a typical chemistry class lab experiment to identify an unknown substance.

As a guess, it’s probably calcium scale, but it could be some contamination from some other source. You’ll probably have more luck asking your water department (assuming you aren’t on your own well) than trying to figure it out yourself.

And a note: I’m not sure how you are using “organic.” In the chemistry sense, it means a compound based on carbon, so a mineral would not be organic. If you mean “not treated with pesticides/herbicides,” it’s certainly possible for tap water to be contaminated although that probably doesn’t manifest as a white powder. If you just mean “nothing dangerous,” it’s unlikely the substance is dangerous but certainly possible.

Dry it out and add a drop of acid to a small sample (strong vinegar will do) if it fizzes, it’s probably calcium carbonate limescale.

If not, it may be some sort of silicate or clay

There are plenty of organic minerals, including calcium carbonate, the most likely culprit.

Go to Home Depot. Ask for a free water test kit. Put a sample of your water in it and mail it off. You’ll get a response in about 30 days.

What definition of organic are you using? Back in my chemistry days, no minerals were considered organic (although there was an organic class added fairly recently for some rare minerals). Under any definition I’ve seen, calcium carbonate is inorganic - either because it is explicitly excluded or because the definition follows something like this:

Yours, from post #2, looks like.

A marquis reagent kit which is really cheap won’t tell you exactly what it is, but with some educated guessing beforehand you should be able to use it to get close.

And yet methane is just as “clearly inorganic” as carbonate. In what way does requiring hydrogen make it a better definition?

Organic did once mean that it had been created by an organism. There was an attitude that really smacked of pseudo-scientific “life force” that organic compounds were not otherwise synthesisable. Something that took a bit of a battering when urea was synthesised ab-initio.

The trouble with the calcium carbonate versus methane argument is that it is almost certain that any natural occurrence of either was the result of biological action. Trouble is, it is hard to get ones head around massive deposits of limestone as actually biogenic. Coal deposits are of course biogenic too, but raw carbon isn’t considered organic either. The bound methane is.

The work “organic” is so debased now that it should be retired.

Or at least acknowledged as meaningless, usable only as a marketing term. (Not a very noble use, but who knows what rampage marketing types would go on if you take meaningless-but-sexy terms like “organic” or “all-natural” from their arsenal?)

I was under the impression that all minerals in tap water were organic. From what I have read, only organic minerals can be absorbed by an organism/us.

This soft white powder is in the water only once every month or two so it seems very strange to me.

I don’t mind spending some money on chemicals and equipment (not too much though), to narrow it down.

I mixed some of this with vinegar and it began to fizz, and hiss, so that means it is calcium yes? If there a way to narrow it down some more or is just calcium.

Way way back in the dark ages of the internet, “Organic Chemistry” was the study of tetravalent carbon and all her compounds except carbon dioxide. “Biochemistry” was the study of compounds involved in living things (which includes calcium carbonate). Iron is found in tap water, which wouldn’t be (necessarily) an “organic compound”, yet clearly it’s important to biochemistry.

I think the OP could pick up a used mass spectrometer for less than $1,000 US. However, if the substance fizzed with acid, then calcium carbonate is the most likely species.

Minerals are for the most part not organic. Salts might be a more useful term than minerals for stuff in tap water, but there isn’t much in it. Minerals are what the name says to some extent - stuff derived from stuff in the ground. When salts are dissolved in water they dissociate - so adding table salt (sodium chloride) doesn’t get you water with sodium chloride in it - you get sodium and chlorine ions. Potasium chloride added to this just means potassium, sodium and chlorine ions all wandering around. And so it goes. If, like most tap water, it is derived from rainfall and run-off from land you will get a huge cocktail of elements (mostly metals) dissolving in it. Calcium, iron, arsenic, and so it goes. That is your mineral content. Most of that stuff will be adsorbed by your gut. Nothing about being organic has anything to do with whether you adsorb it or not.

Water from aquifers or other underground sources is often loaded with dissolved calcium, which leads to the properties that make it “hard”.

Water can only hold so much of a dissolved thing, and how much it can hold is somewhat complicated. Hotter water in general holds more. But when particular pairings of elements are both present in water, they can decide that they prefer not to be dissolved and would prefer to drop out of the water (to precipitate) as a solid. A classic test for chlorine in water is to add some silver nitrate. Silver will stay dissolved if paired with nitrate ions, but if it finds any chlorine ions in the water the pair will precipitate out as a while cloud of silver chloride particles. You can get other things happening, that might mean dissolved calcium in the water is being precipitated out as calcium carbonate. This is how lime scale comes into existence.

Your white powder won’t be pure calcium (that is a somewhat reactive metal) but calcium carbonate. The fizzing is the acid causing a reaction that releases carbon dioxide (which is obtained from the carbonate part). The fact that it does fizz isn’t an absolute diagnostic for calcium carbonate, but given the circumstances, it is a smoking gun with a hot barrel. Simple silica sands wouldn’t fizz for instance.

I wasn’t trying to be snarky when I asked what definition you were using. As noted, there are so many definitions in use that it really doesn’t mean much anymore. (Said as a former physical chemist who didn’t see much point in drawing a line between organic and inorganic.)

G-Wiz, as Francis Vaughan says, the fizzing is a very strong indication that it is calcium carbonate and nothing to worry about. As for why it might be sporadic, some water departments use a mix of surface water and ground water. If you are in one of these areas, you might be seeing the white residue during times when the mix is more heavily weighted to ground water (which is generally higher in dissolved solids).

Let’s back up: is this substance something that settles out of your tap water if you let it sit for a day, is it something that’s left in the pot when you boil away a pot of water (or let it sit until it all evaporates), or does it show up some other way?

It is left at the bottom of my distiller.

There is just too much random crap in tap water, I don’t know how anyone can drink it.

Based on your description and how you found it, I would suspect sodium bicarbonate or one of the hydrates of sodium carbonate. Calcium carbonate is not very soluble, and tends to precipitate as hard mineral-like scales and crusts. It’s the carbonate that is basic, so that it dissolves in acid (or reacts with it) is not diagnostic of which mineral it is.

I wouldn’t call it “crap.” It’s a perfectly ordinary dissolved mineral, and water with dissolved minerals generally tastes better. Pure distilled water tastes flat and stale. If you had a wonderful spring of mountain water, it would be chock full of stuff like this from its sojourn underground. (Another way to put this is that if what you have is one of the carbonate or bicarbonate compounds of sodium, you got it from the interaction of ordinary table salt and dissolved carbon dioxide from the air. You can’t get more innocuous and natural than that.)

The stuff that you would really want to worry about in your water is not especially amenable to home treatment.

Your single largest concern would be living organisms, bacteria, tiny worms, protozoans, et cetera, of the type that cause typhoid, giardia, cholera, et cetera. There is unfortunately no way to tell by eye or taste that water is contaminated with these buggers – the water can look clean and sparkly and certainly leave no residue – but give you a terrible case of the runs, parasitic worms, or in the worst case if untreated kill you. It’s for this reason that the primary concern of water treatment is always to make it sterile – kill anything in it. Almost all other concerns are pretty secondary, in part because it isn’t all that easy to make water sterile cheaply while not making it taste awful or worse. Home remedies are expensive and inconvenient – boiling, for example, or very fine filtering – or make it taste bad, e.g. iodine.

Your next concern would probably be heavy metal contamination, e.g. small amounts of dissolved lead, mercury, arsenic, cadmium. These are unusual, but if you’re downstream from some giant industrial or mining operation in a third-world nation, that might be a problem. Again, these contaminants are impossible to detect by eye or taste, and even much homebrew chemistry. They’re not promptly dangerous, but exposure over time (years) can have significant bad effects, particularly on children.

Finally you might worry about organic contaminants in the sense of PCBs, pesticides, solvents, gasoline, et cetera, stuff that might get into the water stream by various kinds of industrial, commercial and even residential pollution. These however are often detectable by eye or taste at about the same level where they become dangerous, at least promptly dangerous. Few people will willingly drink water with enough dry cleaning fluid e in it to be actually a problem, since it would taste foul.