Consider a 1.50-g mixture of magnesium nitrate and magnesium chloride. After dissolving this mixture in water, 0.500M of silver nitrate is added dropwise until precipitate formation is complete. The mass of the white precipitate formed is 0.641 g. Calculate the mass percent of magnesium chloride in the mixture?

0.641 g AgCl x (1 mole MgCl2/2 moles AgCl) = 0.641 x (95.21/2*143.32) =?? g MgCl2.

% MgCl2 = (g MgCl2/1.5 g sample)*100 = ??
% Mg(NO3)2 = 100 - %MgCl2.

To calculate the mass percent of magnesium chloride in the mixture, we first need to determine the number of moles of magnesium chloride (MgCl2) and magnesium nitrate (Mg(NO3)2) present in the original mixture.

1. Calculate the moles of silver nitrate (AgNO3) required to precipitate all chloride ions from the magnesium chloride:

Since 1 mole of silver nitrate reacts with 2 moles of chloride ions:
Number of moles of AgNO3 required = 2 × (mass of chloride precipitate formed / molar mass of AgNO3)
= 2 × (0.641 g / 169.87 g/mol)

2. Determine the moles of chloride ions initially present in the mixture using the stoichiometry of the reaction between AgNO3 and MgCl2:

Since 1 mole of silver nitrate reacts with 2 moles of chloride ions, and assuming complete precipitation:
Number of moles of MgCl2 = (Number of moles of AgNO3 required / 2)

3. Calculate the moles of magnesium nitrate (Mg(NO3)2) present:

Subtracting the moles of MgCl2 from the total moles of magnesium ions:
Number of moles of Mg(NO3)2 = (Total moles of magnesium ions - Number of moles of MgCl2)

4. Calculate the mass percent of MgCl2 in the mixture:

Mass percent = (Mass of MgCl2 / Total mass of the mixture) × 100

Now that we have determined the steps to solve the problem, let's calculate the values.

First, we need to find the number of moles of AgNO3 required:

Mass of chloride precipitate formed = 0.641 g
Molar mass of AgNO3 = 169.87 g/mol

Number of moles of AgNO3 required = 2 × (0.641 g / 169.87 g/mol)

Once we have the number of moles of AgNO3 required, we can find the number of moles of MgCl2 and Mg(NO3)2:

Number of moles of MgCl2 = (Number of moles of AgNO3 required / 2)

Total moles of magnesium ions = (Number of moles of MgCl2) + (Number of moles Mg(NO3)2)

Number of moles of Mg(NO3)2 = (Total moles of magnesium ions - Number of moles of MgCl2)

Finally, we can calculate the mass percent of MgCl2:

Mass of MgCl2 = (Number of moles of MgCl2 × Molar mass of MgCl2)
Total mass of the mixture = (Mass of MgCl2 + Mass of Mg(NO3)2)

Mass percent = (Mass of MgCl2 / Total mass of the mixture) × 100

By substituting the calculated values into the equations, we can find the mass percent of magnesium chloride in the mixture.