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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: jimi on March 29, 2010, 08:07:47 AM

Title: Convert wt% Mg into mole% MgCO3
Post by: jimi on March 29, 2010, 08:07:47 AM

Hi!
I was examing high-magnesium calcite skeletons using EDS detektor.
I received the following data:


 Elem     Wt %  At %
  C K   12.71  21.00 
  O K   46.93  58.21 
  NaK    0.49   0.42 
  MgK    2.24   1.83 
  SrL    0.45   0.10 
  S K    0.27   0.17 
  CaK   36.91  18.28 
Total  100.00 100.00

How to convert these results in mole% MgCO3?
I would be grateful for help.
Cheers,
jimi

Title: Re: Convert wt% Mg into mole% MgCO3
Post by: sjb on March 29, 2010, 02:29:22 PM

Assume that your sample weighed 100g, now, how much Mg, C and O do you have, in mass, moles? What is the limiting factor?

Title: Re: Convert wt% Mg into mole% MgCO3
Post by: jimi on March 30, 2010, 04:59:05 AM

assume 100 grams of sample
Wt % of Mg, C and O are 2.24,  12.71,   and 46.93 respectively.
Moles of Mg, C and O are  0.14   1.058  and 2.93 respectively.
Please note that the material investigated is high magnesium calcite (CaCO3), but I need to find MgCO3.

I do not know what do you mean by: "the limiting factor"?

Title: Re: Convert wt% Mg into mole% MgCO3
Post by: sjb on April 01, 2010, 04:05:11 PM

If you have 0.14 mol of Mg, how much MgCO₃ can you make? If you have 1.058 mol of C, how much?

How do you intend to partition the carbonate between calcium and magnesium, or indeed strontium and sodium as well?