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### Topic: Original Concentration  (Read 4703 times)

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#### ziagemini

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##### Original Concentration
« on: July 10, 2012, 09:23:03 AM »
Hello All,

i have a question regarding the concentrations. I have a sample i dilute it mass-maas. 30grams of sample+600grams of DW. Then i find the concentration of acetic acid present. It is 0.04M. Now how much is the concentration of acetic acid in original sample. As i did 1:20 dilution. And i remember we have to multiply this so in original solution acetic acid concentration is= 0.04M*20=> 0.8M.

Am i right? Thanks for the help.

Regards!

#### sjb

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##### Re: Original Concentration
« Reply #1 on: July 10, 2012, 10:11:35 AM »
Hello All,

i have a question regarding the concentrations. I have a sample i dilute it mass-maas. 30grams of sample+600grams of DW. Then i find the concentration of acetic acid present. It is 0.04M. Now how much is the concentration of acetic acid in original sample. As i did 1:20 dilution. And i remember we have to multiply this so in original solution acetic acid concentration is= 0.04M*20=> 0.8M.

Am i right? Thanks for the help.

Regards!

Not quite. What is the total mass of your diluted solution.

#### ziagemini

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##### Re: Original Concentration
« Reply #2 on: July 11, 2012, 04:28:24 AM »
The total mass:

Original sample= 31.10 grams
Total mass after dilution = 653.54 grams

Hope this helps.

Regards!

#### sjb

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##### Re: Original Concentration
« Reply #3 on: July 11, 2012, 06:05:36 AM »
The total mass:

Original sample= 31.10 grams
Total mass after dilution = 653.54 grams

Hope this helps.

Regards!

So is the total mass 20 times the original mass? How does this affect the concentration?

#### ziagemini

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##### Re: Original Concentration
« Reply #4 on: July 11, 2012, 06:34:19 AM »
That's what i want to calculate. I don't know the original concentration. That i want to find out. Is there any general rule for that or it differs from acid to acid.

#### Borek

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##### Re: Original Concentration
« Reply #5 on: July 11, 2012, 06:40:40 AM »
Mass is conserved, so no matter what you dilute amount of substance in the solution after dilution is identical with the mass of the substance that was present in the original sample before dilution.
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#### DrCMS

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##### Re: Original Concentration
« Reply #6 on: July 11, 2012, 06:43:35 AM »