1.84 gram of a mixture of calcium carbonate and magnesium carbonate is strongly heated till no further loss of mass takes place. The residue weights 0.96 g. Calculate the percentage composition of mixture.

Asked by Manoj | 8th Jul, 2013, 09:03: PM

Expert Answer:

CaCO3     ?    CaO + CO2
100gms            56g     44g
 
1. 100gm CaCO3 forms 56 gms CaO
X gm CaCO3 forms 56.x/100 = 0.56x gm CaO
 
2. MgCO3     ?    MgO+ CO2
    84g                  40g    44g
 
84g MgCO3 forms 40g MgO 
Therefore, (1.84 - x)g of MgCO3 forms 40 x (1.84 - x) / 84 g MgO                                                       
 
Total Mass of Cao + MgO from the above 
= 0.56x + 40 x (1.84 - x) / 84 = 0.96g (given)
 
Hence, x = 1
Mass of CaCO3 = 1gm
Mass of MgCO3 = (1.84 - 1)
                       = 0.84g
 
Percentage of CaCO3 in the mixture = 1 x 100 / 1.84
                                                     = 54.35%
 
Percentage of MgCO3 in the mixture = 100 - 54.35 = 45.65%
 
 

Answered by  | 10th Jul, 2013, 02:03: AM

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