[flatpro]

Hey,

I have a solution of 18 wt % (about 1g/ml) I want to make it into a solution of 2 wt % by diluting it with water. Using C1 V1 = C2 V2 could someone show me how to do it. I have tried but seem to be getting muddled somewhere.

Thanks!
flatrpo

 

[JGK]

1 part solution (V₁) x 18 % (C₁)=[1 part solution + 8 Parts water =] 9 Parts (V₂) x C₂

C₂= 1 x 18/9 = 2 (%)

Basically it's a x9 dilution

[dufengtao]

18 wt % is a mass ratio, you should use the equation   a wt % x the mass of solution a = b wt % x the mass of solution b   .  If you must use the  C1 V1 = C2 V2 , you must chang the wt % into molar concentration.

[AWK]

Posted by: dufengtao
18 wt % is a mass ratio, you should use the equation   a wt % x the mass of solution a = b wt % x the mass of solution b   .  If you must use the  C1 V1 = C2 V2 , you must change the wt % into molar concentration.

In some cases it works, eg. density of 18 % acetic acid is around 1.02, and this approximation gives only ~2% error