Sure it'd be easier and cheap to just buy new soda and powder but I'm curious.

I had a jar of either baking soda or powder. The marker with which I'd labeled it rubbed off during a house move and I do not recall which one it was.

Is there an easy way to test if I have a jar of baking powder or soda?

4 Answers 4


Baking powder contains starch, which is insoluble.

Baking soda is completely soluble

Take a small bowl, and put 1/8 tsp of the substance in the bottom.

Add water.

If the substance is bicarbonate of soda, the solution will be completely clear.

If it is baking powder, a cloudy/powdery residue will remain.

(You can also use excess vinegar which gives the same result, and fizzes in a pleasingly sciencey fashion...)

test photo

  • 12
    It's a lot more fun with the "pleasingly sciencey" vinegar fizz :)
    – Davy M
    Commented Jun 29, 2018 at 23:24
  • 5
    To clarify with the vinegar, baking powder still contains baking soda, so both solutions will still fizz, and fizzing is not an indicator of baking soda/powder, but just a fun side effect for both. Is that right? I'm not sure if the level of fizzing would be different.
    – Wolfgang
    Commented Jun 30, 2018 at 19:27
  • 3
    @Wolfgang yeah, the vinegar fizzes either way (maybe a bit more/longer in the baking powder), but the starch doesn't react with it and won't dissolve so it's still there at the end of the reaction.
    – Zanna
    Commented Jun 30, 2018 at 19:34
  • 1
    Just checking, is the contents of the baking soda bowl in the picture supposed to be completely clear? Because it definitely doesn't look it to me.
    – David Z
    Commented Jul 1, 2018 at 10:14
  • 3
    @DavidZ clear is not the same as colorless... the colour helps to see that it's clear i.e. not cloudy, but it's an awful photo and I should make a better one...
    – Zanna
    Commented Jul 1, 2018 at 10:26
  • Lick your finger
  • Dip it in the jar
  • Lick finger again.

If it tastes of:

  • Soap: Soda
  • Very faintly of soap and faintly of starch and slightly fizzes in your mouth: Baking powder

Double Acting Baking powder has baking soda (sodium bicarbonate) AND two acids it in Single Acting only has one acid

You can use this property to test by mixing the unknown substance with some plain water (tap is fine). The mixture might start to bubble slowly, as one of the acids in baking powder will start to act when mixed with water and is now able to react with the base.

Double Acting baking powder also reacts with heat

If you gently heat this, there is another acid that will release when wet and heated. This will further react with the baking soda. This is so it will act slowly as the quickbread or whatever is baking.

Baking soda will only react with an acid

If your white powder in an unmarked bottle does not react under the above conditions, now test it with vinegar. This will confirm that it is a base (likely baking soda)

  • +1: I should have read the ingredients, but couldn't find my glasses, so I ignored the fizzing in my mouth.
    – Fabby
    Commented Jun 29, 2018 at 21:11
  • 2
    Some kinds of baking powder ("single acting") only contain a single acid. If you bake with single-acting baking powder, you need to put the dough or batter in the oven soon after adding the liquid ingedients, because you won't get additional rising from the heat of the oven.
    – AndyB
    Commented Jun 30, 2018 at 17:18
  • @AndyB Good point. Meant to specify 'Double Acting.' TY. Commented Jun 30, 2018 at 17:24

Mix some with water. Baking soda will do nothing. Baking powder will bubble somewhat

  • Comment if you downvote so the poster knows what's up.... Commented Jun 29, 2018 at 20:49
  • 1
    This is the simplest test. Baking powder contains an acid, so it will bubble with any liquid. Baking soda does not, which is why recipes that use it always contain an acidic ingredient (vinegar, lemon juice, buttermilk, or acidic fruits).
    – AndyB
    Commented Jun 30, 2018 at 17:13
  • @MarsJarsGuitars-n-Chars Downvoting without commenting is acceptable behavior on the network. Please do not leave comments which suggest otherwise.
    – rumtscho
    Commented Jul 2, 2018 at 9:51

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