(1) Sodium carbonate needs to be fermented to produce acid before it can be used, while sodium bicarbonate can be added directly to flour for use, because NaHCO3 easily decomposes when heated to produce CO2;

So the answer Because: NaHCO3 easily decomposes when heated, producing CO2;

(2) Organic acids do not dissolve in water, so it can be judged that the white powder is not baking powder. Analyze the ingredients of the white powder based on the phenomenon in the question, and make sure that the three If gas is produced, acid needs to be added. Therefore, the experimental plan is: Experimental operation Experimental phenomenon Experimental conclusion ① Take a small amount of white powder in a test tube, add an appropriate amount of distilled water to dissolve the solid, and there is no other obvious phenomenon. The white powder is not baking powder ② Take a small amount of white powder in the test tube and add a sufficient amount of dilute hydrochloric acid The white powder produced by colorless bubbles must be soda ash;

So the answer is:

? Experimental operation? Experiment, phenomenon? Experimental conclusion? ? ?The white powder is not baking powder? Take Place the white powder in a test tube and drop in dilute hydrochloric acid. ? ? (3) Both sodium carbonate and sodium bicarbonate are soluble in water, and adding hydrochloric acid will produce gas. To distinguish the two, it is necessary to design and verify them based on their chemical properties, so the experimental plan is: Experimental operation? Experiment Phenomenon? Experimental conclusion? Take a small amount of white powder and put it into a test tube, plug it with a single-hole plug with a conduit, and extend the other end of the conduit into the clear lime water to heat the solid. ?If bubbles are generated, the clear lime water will become turbid.

If there is no obvious phenomenon. ?The white powder is baking soda.

The white powder is soda ash. ．

So the answer is:

?Experimental operation?Experimental phenomenon?Experimental conclusion?Put a small amount of white powder into the test tube, plug it with a single-hole plug with a catheter, and insert the other end of the catheter In clarified lime water, heat the solid. ?If there is no obvious phenomenon. ?