sample of silver metal is suspected to be contaminated with zinc. A 0.2365 g portion

of this metal is dissolved in nitric acid and the silver ions precipitated with excess

aqueous NaCl. After filtering and drying, the mass of the precipitate is found to be

0.2865 g. What was the purity of the original silver metal (in %w/w)?

the molar mass of silver chloride is 143.32 g

the molar mass of silver is 107.87 g

so the mass of silver in the processed sample is
... .2865 * 107.87 / 143.32

the processed mass divided by the original sample mass is the purity of the original sample

To find the purity of the original silver metal, we need to determine the amount of impurity (zinc) in the sample.

Here's how we can calculate it:

1. Calculate the mass of silver precipitated:
Mass of precipitate = Mass of silver in the sample = 0.2865 g

2. Determine the amount of silver in the precipitate:
Since the precipitate consists of pure silver chloride (AgCl), we can calculate the amount of silver using its molar mass.
Molar mass of AgCl = atomic mass of Ag + atomic mass of Cl
= 107.87 g/mol + 35.45 g/mol
= 143.32 g/mol

Now, convert the mass of the precipitate to moles of silver:
Moles of silver = Mass of precipitate / Molar mass of AgCl

3. Determine the amount of impurity (zinc) in the sample:
Since zinc doesn't precipitate with NaCl, the excess zinc remains in solution after the silver chloride precipitates. Therefore, we need to subtract the amount of silver from the initial mass of the sample to find the amount of impurity.
Mass of impurity (zinc) = Initial mass of sample - Mass of silver in the precipitate

4. Calculate the purity of silver:
Purity of silver = (Mass of silver / Initial mass of sample) × 100

Let's substitute the given values into these calculations:

Initial mass of sample = 0.2365 g
Mass of precipitate = 0.2865 g
Molar mass of AgCl = 143.32 g/mol

Now we can calculate the purity of the original silver metal.