The waste fixing solution contains a certain amount of AgNO 3. A chemical team collected some waste fixing solution from a photo studio, and prepared to take away the silver as a simple substance.

(2) In silver nitrate solution, both copper and iron can replace silver, but copper and silver do not react with acid, so it is not easy to separate the mixture of silver and copper, while iron can react with acid to generate salt and hydrogen, and the monovalent of copper is higher than that of iron, so the second scheme is more reasonable, and the chemical equation of the reaction is: Fe+2AgNO3 θ Fe (NO3) 2+2AG;

(3) Excess metal is added during the experiment, and the metal mixture and solution are obtained after operation A, that is, the separation of insoluble solid and liquid. The operation is filtering. Filtration is used for glass instruments: beakers, glass rods and funnels. Iron reacts with hydrochloric acid to produce ferrous chloride and hydrogen. Because excess hydrochloric acid is needed, the cations in solution B are: H+, Fe2+;

(4) Because iron powder can be attracted by magnets, magnets can be selected for inspection; Or iron can react with acid to generate hydrogen, and dilute hydrochloric acid is added to the metal powder to observe whether there are bubbles for inspection;

(5) 5) The amount of AgNO3 contained in 20L waste fixing solution =20L× 1.7g? L- 1=34g。

The mass of Ag in 34gAgNO3 = 34g×108170x100% = 21.6g. 。

Recycling silver every year (within 365 days) can save the cost =2 1.6g×365×2 yuan = 15768 yuan.

So the formula is 20×1.7×108170× 2× 365.

Therefore, the answers are: (2) b; ? fe+2agno3═fe(no3)2+2ag；

(3) filtering; ? Funnel; ? H+、Fe2+；

(4) Contact with a magnet to see if the silver powder can be attracted (or take a small amount of silver powder and add dilute hydrochloric acid to see if there are any bubbles released);

(5)20× 1.7× 108 170×2×365.