Analysis of Sedimentary Rock for Magnesium and Calcium Carbonates

Common Ca and Mg Carbonates
CaCO3    Calcite
MgCO3   Magnesite
MgCa(CO3)2   Dolomite


Dolomite, the mineral, is named for the  Dolomites, a mountain range in northern Italy at the Austrian border. 


You will analyze solutions made from recently recovered "Martian sedimentary carbonate rocks" . You will determine their Mg-Ca carbonate composition , information which may provide insight into the drying of the Martian landscape.
(Magnesium Carbonate is much more soluble than Calcium Carbonate)


  To do this:

  • You will be given the mass of Carbonate rock dissolved and the total volume and concentration of HCl used to dissolve it.
  • You will determine the amount of acid required to dissolve all the carbonates by titrating the excess HCl with NaOH of known concentration
  • You will determine the total alkaline earth ions present by titration with EDTA of known concentration.

  From the above data

  • You will make two semi-independent calculations of the Ca-Mg carbonate ratio.

Grams of Carbonate dissolved = molCa(100.09) +  molMg(167.9)
Moles of HCl used up = 2(molCa + molMg)
molCa + molMg = (VEDTA )(MEDTA)


RWK 10/10/2006