DILUTIONS (March 4th, 2011)

Today we learned about Dilutions!
When two solutions are mixed the concentration changes

Dilution is the process of decreasing the concentration by adding a solvent (usually water)
the amount of solute does not change (n1=n2), but the concentration changes!


- Because concentration is mol/L we can write:

• C= n/C...... and n= CV..... and V= n/C

n= # of moles, v= volume in litres


So.... we use:

• C1V1= C2V2

C1V1 is the intial concentration and volume
C2,V2 is the final concentration and volume


Time for some questions:


A 30.0 mL of 11.9 M of Hydrochloric Acid is diluted to a final volume of 30 mL. What is the concentration of the new solution?
*if you look at the volume, it is in mL so don't forget to change that to L!


C1V1= C2V2


(11.9mol/L)(.03L)= C2 (0.3L)
.357 mol = C2 (0.3L)
.357mol= C2
0.3


C2= 1.19 M


100 mL of 0.330 M Li2CO3 is added to 600 mL 0.125 M Li2Co3. Determine the [Li2Co3]


0.10 L x 0.330 mol = 0.033 mol
                        L


0.60 x 0.125 mol = 0.075 mol
                     L


0.033 mol + 0.075 mol = 0.108 mol


Take your volumes (100 mL + 600 mL) Add them together and convert it into units of Liters.


0.108 mol
0.7 L


= 0.154 M


One more?


If 250 mL of water are added to 50.0 mL of 1.00 M BaCo3, what will the final concentration be?


(1.00 mol/L) (.05 L) = C2 (.25L)


0.05 mol = C2
0.25 L


C2 = 0.2 M


Post by Ren