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Ionic concentration / number of ions

by somasimple
Tags: ion, volume
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somasimple
#1
Jul31-08, 12:49 AM
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Hi all,

We use often concentrations in chemical/biological experiments.
It is expressed usually in mili/ mole/cm3 or mm3

Is there a way to know the number of ions contained in a volume?
Is there a way to know the number of ions (or density) on a surface knowing the concentration?

Sorry for these basic questions.
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Borek
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Jul31-08, 03:24 AM
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What is mole definition?
somasimple
#3
Jul31-08, 04:29 AM
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Mole: a chemical mass unit, defined to be 6.022 x 10E23 molecules, atoms, or some other unit.

Consider I'm stupid.

Borek
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Jul31-08, 04:47 AM
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Ionic concentration / number of ions

Quote Quote by somasimple View Post
Mole: a chemical mass unit, defined to be 6.022 x 10E23 molecules, atoms, or some other unit.
Not a mass unit, quantity unit. But you are right - 6.02x1023 of elements. Just an overgrown dozen it is.

Do you know how to calculate number of moles of substance given volume of sample and concentration?
somasimple
#5
Jul31-08, 08:16 AM
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I suppose.
If the concentration is 15 mMole then the number of molecules contained per unit of volume is:

(15/1000)*6.02x10E23
Borek
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Jul31-08, 09:04 AM
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Wasn't that hard
somasimple
#7
Jul31-08, 09:19 AM
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Sure but I'm so lazy...
somasimple
#8
Jul31-08, 09:30 AM
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What is the volume unit on this page?
http://www.ncbi.nlm.nih.gov/books/bv...xnZMXWZZQAN0H9
Borek
#9
Jul31-08, 10:49 AM
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M usually stands for mol/liter.
somasimple
#10
May20-09, 09:22 AM
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Many salt are solvated in water.
How many water molecules are in a liter?
somasimple
#11
May20-09, 09:24 AM
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No matter, I found the response:

1 liter of water has mass about 1000 grams/liter.
Molecular mass of water=18
so No. of moles in 1liter = 1000/18= 55.55 moles
this multiplied by Avogadro's number: 6.022*1023
will give number of water molecules in 1 liter as:
55.55*6.022*1023 ~= 334.52*1023


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