How would you prepare 100.0 ml of. 400 m CaCl2 from a stock solution of 2.00 M CaCl2?

C₀=2 mol/l

c₁=0.400 mol/l

v₁=100.0 ml = 0.1 l

c₁v₁=c₀v₀

v₀=c₁v₁/c₀

v (H₂O) = v₁-v₀

v₀=0.1*0.400/2=0.02 l = 20 ml

v (H₂O) = 100 - 20 = 80 ml

It is necessary to mix 20 ml of the feed solution and 80 ml of water.