When students do the comparative experiment of "Chemical Properties of Acids" in the laboratory, they add 10% dilute sulfuric acid to aluminum sheets, and no obvious phenomenon is found. (1) Xiaocao p

When students do the comparative experiment of "Chemical Properties of Acids" in the laboratory, they add 10% dilute sulfuric acid to aluminum sheets, and no obvious phenomenon is found. (1) Xiaocao proposed. (1) aluminum is easy to form a dense oxide film on its surface to protect it. The reaction begins with the reaction of alumina and sulfuric acid.

So the answer is: dense oxide film.

(2) In the materials provided, sulfuric acid is 10% dilute sulfuric acid and 30% dilute sulfuric acid, so the concentration of sulfuric acid is an experimental variable to be compared.

The design of the experiment is that other conditions are the same, and different sulfuric acids are used for experimental analysis.

So the answer is: the low concentration of dilute sulfuric acid leads to slow reaction speed.

Experimental Operation Experimental Phenomena Conclusion Adding appropriate amount of dilute sulfuric acid with mass fraction of 65,438+00% and 30% to aluminum sheet, and adding 30% acid solution can produce bubbles faster. The higher the concentration of sulfuric acid solution, the more intense the reaction with aluminum. (3) According to the law of conservation of mass, the types of elements will not change before and after the reaction, so carbon dioxide will not be produced after the reaction.

So, the answer is: c; The reactant does not contain carbon.