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
[tex]C1\cdot V1=C2\cdot V2[/tex]3) Change the units of volume
[tex]L=200.00mL\cdot\frac{1L}{1000mL}=0.200L[/tex]4) Plug in known values and solve for V2
[tex]3.49\frac{mg}{L}\cdot0.200L=22.0\frac{mg}{L}\cdot V2[/tex][tex]V2=\frac{3.49\frac{mg}{L}\cdot0.200L^{}}{22.0\frac{mg}{L}}=0.03172L[/tex][tex]0.03172L\cdot\frac{1000mL}{1L}=31.73mL[/tex]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.