Chemistry questions in the third year of junior high school, a big reward !!!!

1.Iron powder, chloride, silver nitrate (AGNO3).

Iron is a reactive metal that displaces hydrogen.

Silver nitrate and chloride ions produce a white precipitate (silver chloride), which is a test method for chloride ions, and the reaction of iron element and sulfuric acid can only produce 2-valent iron, and to generate 3-valent iron, iron must be 3-valent at the beginning: dilute sulfuric acid B: sodium carbonate solution C: hydrochloric acid.

From (1), B can only be a sodium carbonate solution; In dilute sulfuric acid and hydrochloric acid, only hydrochloric acid can produce white precipitate with sodium chloride, so C is hydrochloric acid and A is dilute sulfuric acid.

1: Purple litmus reagent, chloride ion, silver nitrate solution.

The purple litmus reagent turns red when it encounters hydrogen ions, and the silver nitrate solution encounters chloride ions, producing a white precipitate.

2：②fe2o3③fe(oh)3

Fe directly reacts with dilute sulfuric acid to produce Fe(SO4)23: A is dilute sulfuric acid, B is sodium carbonate, and C is hydrochloric acid.

The reaction of sodium carbonate with hydrochloric acid and sulfuric acid produces gas, and the white precipitate may be due to the high concentration of chloride ions in hydrochloric acid that makes the sodium chloride lower than the dissolution equilibrium and precipitate, which is not sure.

cl- agno3

2.It should be fe2 (so4)3 choose 2 3

3.Dilute sulfuric acid, sodium carbonate, hydrochloric acid, sodium chloride should be changed to silver nitrate.

Analysis: 1Hydrogen ions are tested with carbonate to produce gas, indicating that it contains carbonate After testing hydrogen ions, of course, chloride ions are tested with silver ions Producing a white insoluble acid precipitate indicates that chloride ions are present.

2.When 3-valent iron is formed, there is 3-valent iron in the reactant (iron reacts with acid to form 2-valent)2 3 iron is 3-valent.

3.Sodium carbonate reacts with both acids to form gas b is sodium carbonate and chloride ions react with silver ions to form precipitates.

c is hydrochloric acid.

litmus solution (sylvestris red), chlorine, acidic silver nitrate solution (silver chloride precipitate) 2,3 (N is H2O, Fe and sulfuric acid into divalent iron).

b is sodium carbonate (and two other acids produce carbon dioxide).

It is barium chloride, C is sulfuric acid, barium sulfate precipitate, and A is hydrochloric acid.

1.Zinc particles (hydrogen is replaced, and then the detonation test proves that it is hydrogen) chloride ion silver nitrate solution.

2.Note that after the reaction, it is 3-valent iron, and elemental iron can only replace 2-valent iron ions, so use compounds containing 3-valent iron, n for water).

3.It can be determined that b is sodium carbonate.

Is it wrong? How can hydrochloric acid and dilute sulfuric acid and sodium chloride precipitate"] Let's take a look at the question again......

1 Calcium carbonate (a substance that can generate hydrogen) Chloride Silver nitrate Iron ions are all +3 valent.

3 A dilute sulfuric acid b sodium carbonate c hydrochloric acid.

From (1), it can be known that B is sodium carbonate, and the precipitate that can be precipitated with sodium chloride is hydrochloric acid, and the precipitate is AGCL