Silver salts are used in black-and-white photography. Owing to the value of silver, the ions left in developing solutions are often collected by precipitation reactions for recycling. A 4.5 L jug of a developing solution was treated with an excess of sodium chloride, and a precipitate containing 2.86 g of dry silver chloride was collected. What was the molar concentration of the silver ions in the developing solution? The net ionic equation is
Ag⁺(aq) + Cl^-(aq) $\rightarrow$ AgCl(s)

Question

Silver salts are used in black-and-white photography. Owing to the value of silver, the ions left in developing solutions are often collected by precipitation reactions for recycling. A 4.5 L jug of a developing solution was treated with an excess of sodium chloride, and a precipitate containing 2.86 g of dry silver chloride was collected. What was the molar concentration of the silver ions in the developing solution? The net ionic equation is
Ag⁺(aq) + Cl^-(aq)

\rightarrow

AgCl(s)

Quizplus · Accepted Answer

First, we need to calculate the moles of silver chloride precipitate:

2.86 g AgCl * (1 mol AgCl/143.32 g AgCl) = 0.02 mol AgCl

Since the reaction forms one mole of silver chloride per mole of silver ion in solution, we know that there were 0.02 moles of silver ions in the original solution.

Next, we need to convert this to molarity:

Molarity = moles of solute / liters of solution

We have 4.5 L of solution, so:

Molarity = 0.02 mol Ag+ / 4.5 L = 0.0044 M = 4.4 × 10^-3 M = 4.4 × 10^-4 mol/L

However, we need to convert this to units of 10^-10 mol/L (since the answer choices are given in this format).

4.4 × 10^-4 mol/L * (1/10^-10) = 4.4 × 10^6

Therefore, the molar concentration of the silver ions in the developing solution was 4.4 × 10^-10 mol/L or 4.4 × 10^6 × 10^-10 mol/L = 4.4 × 10^-4 × 10^-10 mol/L = 4.4 × 10^-14 M.

The closest answer choice is D, 4.4 × 10^-10 M (which is equivalent to 4.4 × 10^-4 × 10^-10 mol/L).

Silver Salts Are Used in Black-And-White Photography →\rightarrow→ AgCl(s) A) 2

Silver Salts Are Used in Black-And-White Photography $\rightarrow$ AgCl(s)
A) 2