What Does the Molar Composition in Crystal Synthesis Mean?

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The discussion revolves around interpreting a reaction mixture's molar composition from a paper that details the synthesis of a crystal. The composition includes 3.0 SiO2, 1.0 Al2O3, 0.1 NaCl, and 276 H2O. There is confusion regarding whether these values represent molar fractions, as they do not sum to one, leading to the conclusion that they likely represent moles of each compound in solution. This interpretation suggests a significant volume of water, approximately 5 liters. Participants agree that the values can be treated as a ratio, allowing for calculations based on a fixed volume of water, such as 250 ml. The method involves adjusting the moles of each compound according to the established ratio, confirming the approach is valid for determining the required amounts of Al2O3 and NaCl based on the specified water volume.
ch3m
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Hi guys,
I'm facing a problem.
I've read a paper where they tried to synthesise a crystal and they give the following reaction mixture molar composition:
3.0 SiO2
1.0 Al2O3
0.1 NaCl
276 H2O

What does it means?
It can't be the molar fraction since the sum of all the fraction must give 1 as result.
I guess that it should be the mol of each compound in solution, but that means that they have almost 5 L of water... am I right?
 
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ch3m said:
I guess that it should be the mol of each compound in solution, but that means that they have almost 5 L of water... am I right?

That's how I would read the information.

No idea why they reported it this way, perhaps that's a convention used in such papers.
 
Borek said:
That's how I would read the information.

No idea why they reported it this way, perhaps that's a convention used in such papers.

Thanks.

So can I take such values as a ratio??

I mean: 3.0:1.0:0.1:276

So if I fix a volume of 250 ml of water which means 13.877 mol, I need to divide the mols for 276 and then multiply for the ratio.
i.e. for Al2O3 --> 13.887*(1/276) and for NaCl 13.887*(0.1/276)
Right?
 
Looks OK.
 

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