Topic content:
In the following experiments, the oxidant of hydrochloric acid is ()
A. Remove iron powder mixed in copper powder with hydrochloric acid
B. Remove rust with hydrochloric acid
C. React with hydrochloric acid and sodium hydroxide solution
D. Hydrochloric acid reacts with silver nitrate solution to form white precipitate
Best answer:
A. Remove the iron powder mixed in the copper powder with hydrochloric acid. 2HCl+Fe=FeCl2+H2 ↑ occurs, and the valence of H element decreases from+1 to 0, then hydrochloric acid shows oxidation, so A is correct;
B. Use hydrochloric acid to remove rust and generate ferric chloride and water. The chemical valence of each element has not changed. Hydrochloric acid is acidic, so B is wrong;
C. The reaction of hydrochloric acid with sodium hydroxide solution is an acid-base neutralization reaction. The chemical valence of each element has not changed. Hydrochloric acid is acidic, so C is wrong;
D. Hydrochloric acid reacts with silver nitrate solution to form white precipitate, which undergoes a double decomposition reaction. The chemical valence of each element has not changed, so D is wrong
Therefore, A
Answer analysis:
There is no explanation for this question
Test core:
Essence of redox reaction: electron transfer (gain or loss or deviation) Characteristics of redox reaction: valence rise and fall (valence of some elements changes before and after reaction, which is the basis for judging redox reaction)