Question

1. You are asked to make 200 mls of a 20mM working (diluted) solution of NaCl using a 2M stock solution. Record the volume of 2M stock solution and the volume of water you would use the make the working (diluted) solution.

Answer 1

The volume of 2M stock solution added = 2 mL

The volume of water = 198 mL

Step-by-step explanation:

Considering

`Molarity_(working\ solution)* Volume_(working\ solution)=Molarity_(stock\ solution)* Volume_(stock\ solution)`

Given that:

`Molarity_(working\ solution)=20\ mM=0.02\ M`

`Volume_(working\ solution)=200\ mL`

`Volume_(stock\ solution)=?`

`Molarity_(stock\ solution)=2\ M`

So,

`0.02\ M* 200\ mL=2\ M* Volume_(stock\ solution)`

`Volume_(stock\ solution)=(0.02* 200)/(2)\ mL=2\ mL`

The volume of 2M stock solution added = 2 mL

The volume of water = 200 - 2 mL = 198 mL