Fun with Fizz

The information on the previous page about baking soda and baking powder, while coming from an authoritative source, was still knowledge too easily gained from a textbook. Being an experimentalist, and as there was nothing good on TV, I decided to look into this myself. I was rewarded with inspiration, thus establishing the advantage of repeating even simple experiments. The experiments described would not be dramatic enough for a guy since there are no serious explosions; being a woman I am satisfied with a bit of effervescence. (Men: for a list of explosive food experiments on the Web, click here.)

The purpose of this experiment is to determine if gas is released when baking soda and double-acting baking powder are added to cool water. (Now I know some bureacratic-type out there who got an A in undergraduate Biology is saying "What's the null hypothesis? You've got to have a formal statement of the hypothesis and use the scientific method." Get real. In case you don't know it, most hypotheses by actual scientists are made up AFTER the experiment, the real purpose of which is to "Let's see what happens if we do this" or "I have this nifty new instrument, what can I measure?")

I dissolved 1/2 tsp baking soda in a glass of water and 1/2 tsp Davis Double Acting Baking Powder in another glass of water. Davis' D.A. powder contains cornstarch, sodium bicarbonate, and sodium aluminum sulphate (S.A.S).

From the chemistry explained on the previous page we would expect that when either is added to plain water:

  1. baking soda would dissolve but not release any gas
  2. baking powder would release gas.
That's what happened. In addition, I noted that baking soda dissolved completely but the baking powder was cloudy. One possible explanation is that the cornstarch didn't dissolve. A follow-up experiment with 1/2 tsp cornstarch in the same volume confirmed this.

The purpose of this experiment was to determine whether baking soda and baking powder would release gas when acid is added. One tsp of white vinegar was added to the solutions from Experiment 1.

From the chemistry explained on the previous page we would expect that when 1 tsp vinegar (acid) is added, gas (noted as effervescence) would be released from the baking soda solution but not the baking powder or control cornstarch solutions. That is what was observed.

The purpose of this experiment was to determine whether baking soda and baking powder solutions would release gas when heated.

To this end, I subjected one glass each with 1/2 tsp baking soda, baking powder or cornstarch to 700 watts heating in a microwave oven for 1 minute. From the notes on the previous page we would expect that little or no gas would be released when the baking soda solution was heated, gas would be released when the baking powder solution is heated, and the cornstarch solution would explode. These predictions were confirmed. (Not the cornstarch one, ha ha! Just trying to see if you're still awake for experiment 3).

The inspiration came in as I contemplated the cloudiness of the baking powder solution when I made it. Cloudiness means that something is not dissolving. Of course most of that was probably cornstarch, but then I realized that the other ingredients might not be dissolving either in cool water. Warming the solution probably increases the solubility in water.

Sooooo, my guess is that the S.A.S. dissolves as the product is heated. As it dissolves, more is in solution to react with the bicarbonate which is already dissolved. Consequently the formation of CO2 increases as the temperature increases. How does that sound?

One experiment that I should do is to compare the amount of gas released from baking powder solutions, one of which having had sufficient acid added to discharge all of the bicarbonate and the second solution without added acid. There should be less gas evolved from the solution to which acid has been added. Well, I'll leave those experiments to someone with a dishwasher!

Updated: May 25, 1996
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