Question

The concentration of the initial stock solution is 3.00 M. The first dilution is made by measuring 10.00 mL with a volumetric pipet and diluting in a 100 mL volumetric flask. What is the concentration of the first solution?

The second solution is made by measuring 25.00 mL of the first solution and diluting in a 100 mL volumetric flask. What is the concentration of the second solution?

The third solution is made by measuring 50.00 mL of the second solution and diluting in a 250 mL volumetric flask. What is the concentration of the third solution?

The fourth solution is made by measuring 1.00 mL of the third solution and diluting in a 500 mL volumetric flask. What is the concentration of the fourth solution?

Answer 1

It is calculated by using the formula

Final Concentration = (Stock concentration x Stock volume)/Final Volume

In First Dilution

Stock concentration = 3.00 M

Stock Volume = 10 mL

Final Volume = 100 mL

So Final Concentration = (3 x 10)/100

Final Concentration of first dilution = 0.3 M or 300 mM

In Second solution

Stock concentration from first dilution = 0.3 M

Stock Volume = 25 mL

Final Volume = 100 mL

So Final Concentration = (0.3 x 25)/100

Final Concentration of Second dilution = 0.075 M or 75 mM

In Third solution

Stock concentration from second dilution = 0.075 M

Stock Volume = 50 mL

Final Volume = 250 mL

So Final Concentration = (0.075 x 50)/250

Final Concentration of Third dilution = 0.015 M or 15 mM

In Fourth solution

Stock concentration from Third dilution = 0.015 M

Stock Volume = 1 mL

Final Volume = 500 mL

So Final Concentration = (0.015 x 1)/500

Final Concentration of Third dilution = 0.00003 M or 0.03 mM