A classmate found that the silver ornaments of Miao nationality are beautiful and full of national culture when traveling, so Fe(NO3)3 solution can be used as an etchant when making silver ornaments.

[Verification hypothesis] (1)① Lavender Fe(N03)3? 9H20 crystal (analytically pure, Mr=404) is prepared into 100mL 1.5mol/L Fe(NO3)3 solution, and the amount of ferric nitrate solute is 0. 15mol, so the crystal quality is required to be 0.15 mol×.

So the answer is: 60.6; 100? ML volumetric flask, rubber pointed dropper;

② The pH value of Fe(NO3)3 solution with 1 .5 mol/L is about1,which indicates that the solution is acidic and is the reason for the hydrolysis of iron ions. The ionic equation of the reaction is Fe3++3H2O? Fe(OH)3+3H+；

So the answer is: Fe3++3H2O? Fe(OH)3+3H+；

(3) Add HN03 solution with pH= 1 into the test tube plated with silver mirror and oscillate. It was observed that the silver mirror dissolved slowly, producing colorless gas, which turned red-brown above the liquid level. The ionic equation of the reaction in solution should be 3ag+NO3-+4h+═ 3ag+NO ↑+2H2O;

Therefore, the answer is: 3ag+NO3-+4h+═ 3ag++NO ↑+2H2O;

(2) In Hypothesis 2, the oxidizability of iron ions is related to the concentration of iron ions, and the generated silver ions generate silver chloride precipitation in the solution to prevent the reaction from proceeding, possibly because the concentration is low or the reaction is prevented, so it is necessary to verify whether the iron ions have a reduction reaction. Did not check whether Fe2+ was generated, it may be that Fe3+ reacted with Ag, but the generated Ag+ and Cl- formed a precipitate to prevent the reaction from continuing, or it may be that the concentration of FeCl3 solution was too small to dissolve silver, so it disagreed with B's conclusion;

So the answer is: disagree; Did not check whether Fe2+ was generated. It may be that Fe3+ reacted with Ag, but the generated Ag+ and Cl- formed a precipitate, which prevented the reaction from continuing. It is also possible that the concentration of FeCl3 solution is too small to dissolve silver.

[Thinking and Communication] It is known that nitric acid with the same concentration is slightly more oxidizing than Fe3+. Based on the above information analysis, the principle of dissolving silver mirror in concentrated and diluted Fe(NO3)3 solution is different. In concentrated Fe(NO3)3 solution, both Fe3+ and NO3- oxidize Ag, while in dilute Fe(NO3)3 solution, only NO3- oxidizes Ag.

So the answer is: in Fe(NO3)3 concentrated solution, both Fe3+ and NO3- oxidized Ag, while in Fe(NO3)3 dilute solution, only NO3- oxidized Ag;