Inquiry activity 1: sodium bicarbonate reacts with hydrochloric acid to produce sodium chloride, water and carbon dioxide. We can see that bubbles emerge from conical bottles and balloons expand. The chemical equation is sodium bicarbonate+hydrochloric acid = sodium chloride +H2O+ carbon dioxide. The foaming principle of effervescent tablets in water is the result of the reaction between baking soda and citric acid in ingredients.

So the answer is: a lot of bubbles are generated, balloons expand, and nahco 3+HCl = NaCl+H2O+CO2 = citric acid.

Survey activity 2

Experimental conclusion According to the experimental phenomenon, it is inferred that NaHCO3 will decompose to generate carbon dioxide when heated, while Na2CO3 will not decompose when heated, so the above conjecture is wrong. The chemical equation of limewater turbidity in beaker C is Ca (OH) 2+CO2 ═ CaCO3 ↓+H2O.

Discussion Ⅱ: Because the sodium bicarbonate solution is alkaline, it cannot be inferred that it must be sodium hydroxide according to the red change of phenolphthalein.

According to the solubility of the substance, calcium ions can be used to identify carbonate, so calcium hydroxide solution can be added.

Extension and application

(1) Sodium bicarbonate is easy to decompose when heated, so a small amount of NaHCO3 is mixed in Na2CO3 solid. Can be removed by heating.

Because sodium bicarbonate is unstable, it should be sealed and stored in a cool place.

So the answer is: the experimental conclusion of carbon dioxide is wrong: Ca (OH) 2+CO2 ═ CaCO3 ↓+H2O.

Communication and discussion Ⅱ. The aqueous solution of sodium carbonate and sodium hydroxide is alkaline and can turn phenolphthalein red.

Calcium hydroxide.

Extension and application

①C

② Moisture-proof and sun protection.