So the answer is: there is a bubble coming out;
(2) Absorbent cotton stained with anhydrous copper sulfate powder in the middle of the small test tube turns blue, and water drops are generated on the inner wall of the test tube.
So the answer is: absorbent cotton turns blue, and water drops are produced on the inner wall of the test tube;
(3) Sodium bicarbonate is decomposed by heating to generate carbon dioxide gas, and carbon dioxide reacts with clarified limewater to generate calcium carbonate precipitation, so bubbles are generated in the air duct in beaker B, and the clarified limewater becomes turbid.
So the answer is: there are bubbles in the airway of beaker B, and the clarified lime water becomes turbid;
(2) At the end of the experiment, special attention should be paid to the operation: first take the airway out of beaker A and beaker B, and then stop heating to prevent back suction.
So the answer is: first take out the airway of beaker A and beaker B, and then stop heating to prevent back suction;
(3) The chemical equation of the reaction during the experiment is as follows: Ⅰ. Sodium bicarbonate is decomposed by heating to produce sodium carbonate, carbon dioxide gas and water: 2NaHCO3△. Na2CO3+CO2↑+H2O，
So the answer is: 2 nahco3 delta. na2co 3+CO2 ↑+ H2O；
Ⅱ. Colorless reacts with water to produce copper sulfate pentahydrate. The chemical equation of the reaction is: CuSO4+5H2O=CuSO4? 5H2O，
So the answer is: CuSO4+5H2O=CuSO4? 5H2O
Three. Carbon dioxide reacts with clear limewater to produce calcium carbonate precipitation and water. The chemical equation of the reaction is: CO2+Ca(OH)2═CaCO3↓+H2O.
Therefore, the answer is: CO2+Ca (OH) 2 ═ CaCO3 ↓+H2O.