Molality = [moles of solute(mol)/weight of solvent(kg)] x 1000
Molarity also known as the molar concentration of a solution is defined as the moles of a solute per liters of a solution. It is denoted by M.
Molality can be related to molarity using the density of the solution as
m = Mx1000/ (1000ρ - Mxw)
Where M = Molarity
m = molality
ρ = density of the solution in g/ml
w = molecular weight (molar mass) of solute in g/mole
Here, w = 58.44 g/ml
So, m = 3x1000 / (1000x1.25 - 3x58.44)
= 3000 / (1250 - 175.32)
= 3000 / 1074.68
= 2.79 mol/kg
Therefore, the required molality is 2.79 mol/kg.
The density of the 3M solution of NaCl is 1.25 grams per ml. Calculate the molality of the Solution.
The density of the 3M solution of NaCl is 1.25 grams per ml. The molality of the solution is 2.79 m.
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