Question

Calculate the formal concentration of a sodium acetate solution prepared by diluting 45.0 mL of a solution containing 25.0 ppm sodium acetate (NaC₂H₃O₂, FM=82.03 g/mol) to a total of 0.500 liters of solution.

Answer 1

Concentration of 25.0ppm sodium acetate solution i.e. 25mg/1L of sodium acetate solution can be expressed in moles/L as follows

Moles per Liter of sodium acetate = 0.025 g/L x 1mol/82.03g

Moles per Liter of sodium acetate = 3.05 x 10^-4 mol/L

Therefore, concentration of 0.045L of 3.05 x 10^-4 mol/L solution upon dilution to 0.500 liters can be calculated as follows:

M1V1 = M2V2

3.05 x 10^-4 mol/L   x 0.045L = M2 x 0.500 L

M2 = 2.75 x 10^-5 mol/L

M2 = 2.75 x 10^-5 M

Thus, formal concentration of sodium acetate solution will be 2.75 x 10^-5 M