| (1) cotton balls turn blue, B bubbles and lime water becomes white and cloudy, at the beginning of the A bubbles, droplets appear in the small test tube (2) to prevent backsiphonage (or first from the two beakers to remove the gas guide tube and then remove the alcohol lamp) (3) NaHCO 3 is less thermally stable than Na 2 CO 3, the decomposition of NaHCO 3 has CO 2 and CO 3, and the decomposition of NaHCO 3 has CO 2 and CO 2, the decomposition of NaHCO 3 has CO 2 and CO 2. CO 2 and H 2 O are produced by the decomposition of NaHCO 3 |