Question

A solution contains 3.08 g of dissolved silver.

How many moles of potassium chloride must be added to the solution to completely precipitate all of the silver?
What mass of potassium chloride must be added?

Answer 1

To determine the moles of potassium chloride required to completely precipitate all of the silver, we first need to write a balanced chemical equation for the reaction between silver and potassium chloride. The balanced chemical equation is:

AgNO3 + KCl → AgCl + KNO3

This equation shows that 1 mole of AgNO3 reacts with 1 mole of KCl to produce 1 mole of AgCl.

Next, we can calculate the moles of silver in the solution using its molar mass:

moles of Ag = mass / molar mass

moles of Ag = 3.08 g / 107.87 g/mol

moles of Ag = 0.0286 mol

Since the reaction between silver and potassium chloride is 1:1, we need the same number of moles of KCl as the number of moles of Ag:

moles of KCl = 0.0286 mol

Finally, to determine the mass of KCl required, we can use its molar mass:

mass of KCl = moles of KCl x molar mass

mass of KCl = 0.0286 mol x 74.55 g/mol

mass of KCl = 2.13 g

Therefore, we need to add 0.0286 moles of KCl (equivalent to 2.13 g) to completely precipitate all of the silver.