Dilution

[MrWizard]

Alright so I did have all of the equations written quite nicely before but I clicked back and all that time spent typing the equation with the correct subscripts and all, but I realize I don't not really need all the information to understand this step. Basically I am doing a titration lab but I am having problem with dilution:

 

It seems they want me to dilute it twice before titration, Solution X than use Solution X for Solution Y. Solution Y is what will be used for titration.

 

Borax: 3.115x10^-3 mol

Dilute into a 100ml (0.1L) flask which will become known as Solution X: 3.115x10^-2 M Borax

 

Now this following part is where the confusion lyes, I don't know if it is the wording or a miscalculation, this is the procedure:

 

"To acheive the following dilution, transfer some Solution X to a clean beaker. Pipette 10.0mL into a 100mL volumetric flask and make up with distilled water."

 

I know I am supposed to use c1v1=c2v2 but the answer comes out to a factor of 10 higher

c1 = 3.115x10^-2 M and v1 = 0.01 L ? (10mL of the Pipette)

v2 = .1 L (100mL)

 

which makes  c2 = 3.115x10^-1 M

 

 

 

[cypress]

It's your math MrWizzard. C₂ = (V₁/V₂)*C₁

 

so C₂ = (0.01/0.1)* 3.115x10-2 M

[MrWizard]

so does that mean it stay the same after dilution? o.O

[cypress]

No 0.01/0.1 = 0.1 so it will be diluted by a factor of 10 just as you would expect if you add 90 ml solvent to 10 ml solute.

[mississippichem]

No 0.01/0.1 = 0.1 so it will be diluted by a factor of 10 just as you would expect if you add 90 ml solvent to 10 ml solute.

 

Sorry, not to be picky. But the above calculation doesn't account for the complex relationship between solvent/solute volume and solution volume. Though your extrapolation is reasonable and approximately correct for the general chemistry student, the volume of solute can't really be claimed. Sorry again, you can accuse me of being a "purist" if you want.

[cypress]

True that the relationship between solvent added and final volume is not likely to be perfectly linear so I should not have said that 90 ml solvent was to be added. Thanks for the correction. It is correct though that the final dilution factor is 10 to 1 by volume and thus the final concentration is 1/10th the original in that the solute volume was 10 ml and the final volume is 100 ml.

 

Again your precision to detail is appreciated.