Question

A stock solution of 50 mg/mL NaCl has been prepared. A working stock (1:10) of this salt solution must be prepared for experiments.

What is the concentration of the working (1:10) stock in mg/mL?

How would you make 10 mL total diluted working stock solution?

How would you make 1 mL total diluted working stock solution?

Answer 1

Stock solution = 50 mg/ml

Working stock solution = 1:10

This means that 1 ml of 50 mg/ml and 9 ml of water.

Concentration = 50 mg/10 ml = 5 mg/ml

The available concentration = C1 = 50 mg/ml

Volume = V1 = ?

Concentration required = C2 = 5 mg/ml

Volume = V2 = 10 ml

C1V1 = C2V2

50*V1 = 5*10

V1 = 1 ml

So, to make 10 ml of total diluted working stock solution, 1 ml of stock solution is dissolved in 9 ml of water.

The available concentration = C1 = 50 mg/ml

Volume = V1 = ?

Concentration required = C2 = 5 mg/ml

Volume = V2 = 1 ml

C1V1 = C2V2

50*V1 = 5*1

V1 = 10 ml

So, 1 ml of diluted stock solution from stock solution can not be prepared. As the volume is coming out to be 10 ml but we need total solution to be 1 ml.