Question

Calculate the final concentrations of the following aqueous solutions after each has been diltuted to a final volume of 25.0 mL:

a) 1.00 mL of .463 M Na+

b) 2.00 mL of 3.45 mM LiCl (in mM)

c) 5.00 mL of .0645 mM Zn2+ (in mM)

Answer 1

a) 1.00 mL of .463 M Na+

Millimoles of Na+ = 0.463 x 1 = 0.463 mmol

Final Volume = 25 mL

=> Molarity = 0.463 / 25 = 0.01852 M or 18.52 mM

b) 2.00 mL of 3.45 mM LiCl (in mM)

Millimoles of LiCl = 3.45 x 0.02 = 0.069 mmol

Final Volume = 25 mL

=> Molarity = 0.069 / 25 = 2.76 x 10^-3 M = 2.76 mM

c) 5.00 mL of .0645 mM Zn2+ (in mM)

Millimoles of Zn2+ = 0.0645 x 0.05 = 3.225 x 10^-3 mmol

Final Volume = 25 mL

=> Molarity = 3.225 x 10^-3 / 25 =1.29 x 10^-4 M = 0.129 mM