Question

Hello, I did a lab measuring cellular respiration where I put germinated and non germinated millet seeds in test tubes. I plugged the tubes with cotton soaked in NaOH which is supposed to react with the CO2 and turn it into solid sodium bicarbonate. When I observed the experiment over a two hour period I couldn't see any evidence of the sodium bicarbonate. Observing the cotton does not show any evidence of the sodium bicarbonate, which is where I assume it would be formed. What would the sodium bicarbonate look like in the tube?

Answer 1

When concentration of NaOH is low then CO2 first react with NaOH and forms carbonic acid. This carbonic acid then reacts with NaOH to form sodium bicarbonate. Carbonic acid is liquid, therefore it will come down into the test tube just after formation by the reaction between NaOH in cotton plug and CO2 producled by seeds and further reaction will take place in test tube. Thus, sodium bicarbonate will be found as solid white deposition in the test tube base along with the side wall of test tube.