Carbonates are found in a variety of different minerals. Below are three examples.Huntite: CaMg3(CO3)3 (MM 353.0), Calcite: CaCO3 (MM 100.1) , Dolomite: CaMg(CO3)3 (MM 184.4)An unknown mineral is received in the lab where it is crushed and pulverized. A 1.00 gram sample is reacted with excess HCl(aq). The expelled carbon dioxide gas is bubbled through 200.0 mL of a 0.100 M Ba(OH)2 solution where it precipitates as BaCO3(s). The remaining filtered solution required 75.0 mL of 0.100 N H2SO4. Determine which mineral was received in the lab.This is a question on an assignment that I could use help with. Does anyone have any suggestions?
Ba(OH)2 + H2SO4 → BaSO4 + 2 H2O 0.100 N H2SO4 0.050 M H2SO4 (75.0 mL) x (0.050 M H2SO4) / (1 mol Ba(OH)2 / 1 mol H2SO4) / 0.100 M Ba(OH)2 37.5 mL excess Ba(OH)2 CO2 + Ba(OH)2 → BaCO3 + H2O (200.0 mL - 37.5 mL) / (1000 mL/L) x (0.100 mol/L Ba(OH)2) x (1 mol CO2 / 1 mol Ba(OH)2) 0.01625 mol CO2 So the ratio in the sample was (0.01625 mol CO2)/gram In the case of the possible carbonate minerals, each carbonate ion generates one molecule of CO2. So the ratios are: CaMg3(CO3)3 3 mol / 353.0 g 0.008499 mol CO2/g CaCO3 1 mol / 100.1 g 0.00999 mol CO2/g CaMg(CO3)3 3 mol / 184.4 g 0.01627 mol CO2/g So the received sample must be Dolomite.
I don't think we actually covered this in class so thank you for the help!
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