Question

Describe how to dilute a 20% stock solution to make 50.00 mL of a 2% solution using a 10 mL graduated cylinder and a 50.00 mL volumetric flask. Show calculations.

Perform similar calculations for 5%, 10%, and 15% solutions. Show work.

Answer 1

Solution :-

Stock solution concentration = 20%

Dilute solution volume = 50 ml

Dilute solution concentration = 2%

Volume of stock solution = ?

The calculation for making 2% solution,

Using the dilution formula we can find the volume of the stock solution needed to make the solution with desired volume and concentration

C1V1=C2V2

V1=C2V2/C1

     = 2% x 50 mL / 20 %

     = 5 mL

Therefore we need to measure 5 mL of the stock solution using the 10 mL graduated cylinder and then transfer it to the 50 mL volume metric flask and fill the flask up to the mark with distilled water.

Calculations for the making 5% solution.

C1V1=C2V2

V1=C2V2/C1

     = 5% x 50 mL / 20 %

     = 12.5 mL

Therefore we need to measure 12.5 mL of the stock solution using the 10 mL graduated cylinder and then transfer it to the 50 mL volume metric flask and fill the flask up to the mark with distilled water.

The calculation for the making 10% solution.

C1V1=C2V2

V1=C2V2/C1

     = 10% x 50 mL / 20 %

     = 25 mL

Therefore we need to measure 25 mL of the stock solution using the 10 mL graduated cylinder and then transfer it to the 50 mL volume metric flask and fill the flask up to the mark with distilled water.

The calculation for making 15% solution.

C1V1=C2V2

V1=C2V2/C1

     = 15% x 50 mL / 20 %

     = 37.5 mL

Therefore we need to measure 37.5 mL of the stock solution using the 10 mL graduated cylinder and then transfer it to the 50 mL volume metric flask and fill the flask up to the mark with distilled water.