Ask A Scientist© Chemistry Archive

 

 > >   name        Jeffrey
 > >   age         13

 > >   Question -  Vinegar is an acid and baking soda is basic (I think), so
 > > whenever you mix an acid with a base does it always foam?

 >Dear Jeffrey;
Good question. The answer is no, it doesn't always foam when you
mix an acid and a base. It only foams when you mix acids with certain
bases. Acid- base reactions are always of the form
acid + base ---> water + something

where the something is a "salt." NaCl, table salt, is an example.
Most salts that are formed by acid-base reactions are stable,
but some decompose into gases. The salt produced by reacting
the acid in vinegar with baking soda is unstable, and decomposes
to form a gas (CO2, carbon dioxide). This gas produces the foaming.

Best regards,
prof. topper
dept of chemistry
the cooper union
new york, ny
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Hi Jeffrey,

Yes you're right, vinegar and baking soda are acid and basic (slightly).
The reason why it foams is because baking soda has a basic form of carbon
dioxide.  That's what makes the bubbles.  You can get similar bubbling by
adding vinegar to powdered limestone.

Don
Donald Yee Ph.D.                San Francisco Estuary Institute
180 Richmond Field Station,     1325 South 46th St. Richmond, CA  94804
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