[Rhyleigh]

Please forgive me if this sounds stupid, but I just need some feedback to check my answer.

The question is this: The concentration of iron in a solution is 0.0400 mg/mL. A new solution is prepared from this solution by diluting 5.00 mL of the original solution to a final volume of 50.00 mL.  What is the concentration of iron in the diluted solution?

I converted the 0.0400 mg of Fe to moles of Fe.  Then I divided the moles by 5 mL. which gave me the Molarity of Fe in the original solution.  I then took that figure and multiplied it by 50 mL and I got the Molarity of Fe in the final volume.

Is that right?  Your feedback is greatly appreciated.



I really hate these formula questions! I'm never confident of which formula goes to which question.   

[LQ43]

I converted the 0.0400 mg of Fe to moles of Fe.  Then I divided the moles by 5 mL. which gave me the Molarity of Fe in the original solution.  I then took that figure and multiplied it by 50 mL and I got the Molarity of Fe in the final volume.

your first step converting g --> mol Fe is good.
But this #moles is in 1 mL. (0.0400 mg/mL) how many in 1L? ----> use this to get Molarity of original Fe solution

you take 5mL of this original solution ---> how many moles?
this number of moles is in the new diluted solution of 50mL,
how do you get Molarity?

hope this helps

[Rhyleigh]

Thanks! I think I got it now...