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
Answers
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 %