V = 0.260 L = 260 mL
If you give the initial concentration a number, any number, then use C = n/V or n = C*V, one thing you will notice is that n does not change. So your formula becomes
C*V = Cf * Vf
C = 2 mol/L (this number is just made up.)
V = 13 mL
C1 = ????? (you have not added anything but water).
V1 = 260 mL
2 * 13 = 260 x
26 = 260 x
x = 0.100 mol/L
the new concentration is 0.1 moL/L The ratio of old to new is 2/0.1 = 20 which means that the old concentration is 20 times the new.
Now we have to do it the more expected way. n is still the same during the dilution.
C = C
V = 13 mL
C1 = ???
V1 = 260 mL
C * 13 = C1 * 260 mL
C/ C1 = 260 / 13
C / C1 = 20
The old concentration was 20 times the diluted one. If you are having trouble with this idea, drop me a note. I'll see what will get you to understand it.
