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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: kdambros02 on April 25, 2006, 08:46:55 PM

Title: Dilution question for exam..
Post by: kdambros02 on April 25, 2006, 08:46:55 PM

I have a question reguarding Dilution...

A 46.2mL, 0.568 M calcium nitrate [Ca(NO3)2)] solution is mixed with 80.5 mL of 1.396M calcium nitrate solution. Calculate the concentration of the final solution.

Now, the answer in the book says 1.09M. However, I am unsure of how to derive the answer to this problem. I cant even figure out how to set it up. Any input would be appreciated, as my exam is tomorrow night.

Title: Re: Dilution question for exam..
Post by: Yggdrasil on April 25, 2006, 09:14:39 PM

Probably the best way to approach a problem like this is to first figure out the total number of moles in your new solution then to divide that by the total volume.

So, in the 46.2mL, 0.0568M solution there are:
0.0462 L * 0.568 mol/L = 0.0262 mol

And in the 80.5mL, 1.396M solution there are:
0.0805 L * 1.396 mol/L = 0.112 mol

Giving a total of 0.115 mol in your new solution.  Divide this by the total volume of your new soulution (126.7mL = 0.1267 L) and you get a final molarity of 1.09 M.

Title: Re: Dilution question for exam..
Post by: kdambros02 on April 25, 2006, 09:34:11 PM

thanks alot for the assistance