Question

A chemist prepares a solution by adding 422 mg of Co(NO3)2 (MW = 182.94 g/mol ) to a volumetric flask, and then adding water until the total volume of the contents of the flask reaches the calibration line that indicates 750 mL .
a. Determine the molarity of the prepared solution.

Answer 1

Answer:

3.08 × 10⁻³ M

Explanation:

A chemist prepares a solution by adding 422 mg (0.422 g) of Co(NO₃)₂. The moles of solute associated with this mass, considering that the molar mass is 182.94 g/mol, are:

0.422 g × (1 mol/182.94 g) = 2.31 × 10⁻³ mol

The volume of the solution is 750 mL = 0.750 L.

The molarity of Co(NO₃)₂ is:

M = moles of solute / liters of solution

M = 2.31 × 10⁻³ mol / 0.750 L

M = 3.08 × 10⁻³ M