Arley, I have both in my pantry, I'd be happy to make a little arrowroot and Cream of Tarter each meet vinegar this morning..

In fact I will and see if what kind of response they give me....Just for you...:o)

Well there will be no bubbling of either. LOL
However the Cream of Tarter almost immediately started to dissolve in the vinegar, where as the Arrowroot, wants a stir to incorporate.

Terri, thanks for the experiment. The definitive test, I think, is adding a little cream of tartar to a solution of baking soda to see if gas is produced.

That's actually what baking powder is--it's a weak alkali (Sodium Bicarbonate) with a weak acid (cream of tartar, more accurately potassium bitartrate). When water dissolves them, it allows them to react and neutralize each other. A by-product of the reaction is carbon dioxide which causes your biscuits to rise. That's also why baking powder becomes ineffective over time: humidity in the air is absorbed and allows that reaction to take place.

I'll get into my Mr. Wizard mode a little later on and mess around with it.

There is an easy test for starch. Only problem is, it requires tincture of iodine, which hardly anyone has on hand any more. A drop of iodine on the powder will turn dark blue it it's starch.

Iodine can be purchased at the drug store, but may not be worth the cost for what you are doing.

Jim

Just taste it......cream of tartar is sour and gritty on the tongue...arrowroot has no taste at all.
Linda C

Good info, Linda. Also, I believe arrowroot, being a starch, is insoluble until it is cooked. So, when mixed with water, the mixture will remain cloudy, not clear. Then it will clear when boiled. Is that correct?

Jim

Don't know....I just took a touch out of each bottle and tasted it....very VERY different.
Linda C

As far as kitchen science, there are natural PH indicators in the kitchen that can be used to check if something is acid. Red cabbage has a pigment that acts as a PH indicator. You chop the cabbage and cover with boiling water to get the pigment into solution which should be kind of blue/violet. Acids will move it through purple to red (depending on how acidic); bases move it though blue-green to greenish yellow. The other day, I was soaking black beans before cooking and noticed that the water had that same kind of purplish color, so I took some and added acid (white vinegar) - that turned it red too.

But you already know it is an acid because it tastes sour. The baking soda test just confirms this - but that doesn't tell you what white acid powder it is - cream of tartar seems a good guess but there are other white powders that are acids such as sour salt (citric acid).

Maybe you could put 1/8 tsp of it into an egg white, whip it and compare to an egg white whipped without it.

Or you could just take it back to the store.

Here is a link that might be useful: red cabbage indicator instructions

Chemistry is fun, isn't it.

What cloud describes is the basis of litmus paper.

A convenient material for that test is red wine. What do you see when you brush your teeth with alkaline tooth paste after drinking red wine? Red spit or blue? Beet juice and some other things react the same way I believe.

Jim