Question

A 2.559 9 pellet containing NaCl and KCl is dissolved in water. A silver nitrate solution is mixed with water containing the
pellet, and a precipitate forms. The precipitate is separated and dried and found to have a mass of 5.112 9. What is the
percent composition of NaCl and KCl in the pellet? (Molar mass of NaCl = 58.44 g/mol, KCL = 74.55 g/mol, AgCl = 143.32 g/mol)
O 14.1% KCl and 85.9% NaCl
O 36.2% KCl and 63.8% NACI
o 50.0% KCl and 50.0% NaCl
63.8% KCl and 36.2% NaCl
85.9% KCl and 14.1% NACI​

Answer 1

Answer:

ANSWER

The mass of sample is 1.0 g.

The sample is 23% by mass in sodium.

The mass of sodium is

100

23

×1.0=0.23 g

The atomic masses of Na and Cl are 23.0 g/mol and 35.5 g/ mole.

In NaCl, 0.23 g of Na corresponds to

23.0

35.5

×0.23=0.355 g of chlorine.

The molar mass of AgCl is 143.5 g/mol and the atomic mass of Cl is 35.5 g/mol.

A 2.0 g precipitate of AgCl separate out.

2.0 g of AgCl corresponds to

143.5

35.5

×2.0=0.495 g of chlorine.

Out of 0.495 g of chlorine, 0.355 g of chlorine is from NaCl. The remaining 0.495−0.355=0.140 g is from KCl.

The molar mass of KCl is 74.6 g/mol. The atomic mass of chlorine is 35.5 g/mol.

0.140 of chlorine corresponds to

35.5

74.6

×0.140=0.2928 g of KCl.

The mass of sample is 1.0 g. The mass of KCl is 0.294 g. The mass percent of KCl in sample is

1.0

0.2928

×100=29.28 %