Calculating Molarity using Solute Moles

Question

A chemist prepares a solution of magnesium fluoride MgF2 by measuring out 0.0531μmol of magnesium fluoride into a 500.mL volumetric flask and filling the flask to the mark with water.

Calculate the concentration in mol/L of the chemist's magnesium fluoride solution. Be sure your answer has the correct number of significant digits.

Answer 1

The correct number of significant digits in the answer should be 3 because both 0.0531 and 500. have 3 significant digits.

The question asks us to find the concentration in moles/liter. So first we will find the moles:

0.0531 umoles x 1 mole / 10⁶ umoles = 5.31x10^-8 moles

Next, we will find the liters:

500 ml x 1 L / 1000 ml = 0.500 L

So the concentration in moles / liter = 5.31x10^-8 mols / 0.500 L = 1.06x10^-7 mols / L