Question

How many milliliters of stock solution should you measure out and dilute with water?

Answer 1

1) List known values

Initial concentration (C1): 3.49 ppm

Initial volume (V1): 200.00 mL

Final concentration (C2): 22.0 ppm

Final volume (V2): ?

ppm = mg/L

2) Set the equation

`C1\cdot V1=C2\cdot V2`

3) Change the units of volume

`L=200.00mL\cdot(1L)/(1000mL)=0.200L`

4) Plug in known values and solve for V2

`3.49(mg)/(L)\cdot0.200L=22.0(mg)/(L)\cdot V2`
`V2=\frac{3.49(mg)/(L)\cdot0.200L^{}}{22.0(mg)/(L)}=0.03172L`
`0.03172L\cdot(1000mL)/(1L)=31.73mL`

If we want to make 200.00 mL of 3.49 ppm solution, we have to measure 31.73 mL of 22.0 ppm solution.