Question

2. A silver recovery unit can process 1500 L of photographic silver waste solution per day. Adding excess solid sodium chloride to a 500 mL sample of the waste gives a white precipitate that, after filtration and drying, consists of 3.73 g of AgCl.

Write the balance ionic equation for the reaction between NaCl and Ag+1 ions.

What mass of NaCl must be added to the 1500 L of silver waste to ensure that all the Ag+ ions precipitate?

How many grams of Ag recovered from 1500 L waste?

Answer 1

Ag⁺¹ + NaCl ------> AgCl + Na⁺

^{58.44 NaCl -------->143.32g AgCl}

Density of Ag⁺¹ ----> 10.49 g/cm³ , = 10490 g/L

Density of NaCl ---------> 2.165 g/cm³ = 2165 g/L

Total mass of Ag+1 -----> 10490 X 1500 = 15735000 g

Let x amount of solid sodium chloride is added to a 500 mL sample of the waste forms ----> 3.73 g of AgCl.

in 500 mL waste ..... contain 5245 g Ag+1

5245 g Ag waste reacts to give 3.73 g AgCl

1500 L Ag+1 = 15735000 g Ag+1 ions give ------------> 11190 g AgCl

grams of Ag recovered from 1500 L waste ------> 11190 g AgCl

143.32g AgCl is formed from 58.44 NaCl

To form 11190 g AgCl amount of NaCl needed = ((58.44/143.32)X11190) = 4562.82 g

mass of NaCl must be added to the 1500 L of silver waste to ensure that all the Ag+ ions precipitate = 4562.82 g