Question

The density of a 0.448-m aqueous solution of K2CrO4 is 1.063 g/mL. What is the molarity (M) of this solution? The molar mass if K2CrO4 is 194.2 g/mol.

Answer 1

Molarity for the solution is 0.44 mol/L

Step-by-step explanation:

Let's analyse the data:

0.448 m means molality (mol of solute in 1kg of solvent)

Density = mass / volume and it always refers to solution

The molar mass of the solute, can help us to determine the mass of solute.

For molarity we need the volume of solution; remember that Molarity means the moles of solute in 1L of solution

1kg = 1000 g

Let's determine the mass of solute

0.448 mol . 194.2 g/ mol = 87 g of solute

So we have 87 g of solute and 1000 g of solvent

Mass of solution = Mass of solute + Mass of solvent

Mass of solution = 87 g + 1000 g → 1087 g

Now we can apply density for the volume

1.063 g/mL = 1087 g / Solution volume

Solution volume = 1087 g / 1.063 g/mL →1022.5 mL

Finally we must convert the volume from mL to L

1022.5 mL . 1L / 1000 mL = 1.0225 L

Molarity (mol/L) = 0.448 mol / 1.0225L → 0.44 M