Answer:
A. 11.1%
B. 0.0291
C. 1.57 M
D. 1.67 m
Explanation:
A.
Mass of KCl (solute): 28.0 g
Mass of water (solvent): 225 g
Mass of solution: 28.0 g + 225 g = 253 g
The mass percent of KCl is:
%KCl = (mass of KCl/mass of solution) × 100%
%KCl = (28.0 g/253 g) × 100%
%KCl = 11.1%
B.
The molar mass of KCl is 74.55 g/mol. The moles of KCl are:
28.0 g × (1 mol/74.55 g) = 0.376 mol
The molar mass of water is 18.02 g/mol. The moles of water are:
225 g × (1 mol/18.02 g) = 12.5 mol
The total number of moles is 0.376 mol + 12.5 mol = 12.9 mol.
The mole fraction of KCl is:
X(KCl) = moles of KCl / total moles
X(KCl) = 0.376 mol / 12.9 mol
X(KCl) = 0.0291
C.
The volume of the solution is 239 mL (0.239 L).
The molarity of KCl is:
M = moles of KCl / liters of solution
M = 0.376 mol / 0.239 L
M = 1.57 M
D.
The molality of KCl is:
m = moles of KCl / kilograms of solvent
m = 0.376 mol / 0.225 kg
m = 1.67 m
