A stock solution NaCL solution is 20%. From it prepare 15 mL of 0.9% saline solution. How much of the stock solution do you need? How much water do you ne

Question

Determine the volume of stock solution needed and the volume of diluent

Answer 1

V1C1 = V2C2 in chemistry terminology

V1 = initial volume = ?

C1 = initial concentration = 20%

V2 = final volume = 15 ml

C2 = final concentration = 0.9%

 

(V1)(20%) = (15 ml)(0.9%)

V1 = (15)(0.9)/20 = 0.0.675 ml of the stock solution

15 ml - 0.675 ml = 14.325 ml of diluent

NOTE:  These values are not adjusted to the correct number of significant figures as I'm not sure you are being asked to use such a correction.

 

Answer 2

Hi again Alysha,

 

(.009)(15) = (.20)(x)

 

.135 = .2x

 

.675 = x

 

You need .675 ml of the stock solution

 

15-.675 = 14.325

 

You need 14.325 ml of water