immediately starts bubbling and fizzing (if it
doesn’t, throw out your baking powder and buy a
new can). This is the first reaction. After 30
seconds or so, all action will cease, and you’ll end
up with a still pool of chalky-looking liquid.
Now microwave that liquid for about 15 seconds
to bring it up to 180°F. A second, vigorous batch
of bubbling should occur. You may also notice the
liquid thicken slightly.
Results and AnalysisWhen the baking powder first gets wet, a reaction
occurs between the sodium bicarbonate and one of
the powdered acids, typically potassium bitartrate
(aka cream of tartar), producing the first batch of
bubbles. The second phase of the double act occurs
only at higher temperatures (around 170° to 180°F),
when a second powdered acid (typically sodium
aluminum sulfate) reacts with the remaining sodium
bicarbonate, producing another round of bubbles.
The thickening action is a side effect of the starch
used to keep the baking powder dry—it absorbs
water and gelatinizes, thickening your liquid as it
heats. Now isn’t that way cooler than that baking
soda volcano you built for your fourth-grade science
fair?
MIXING BATTER