supposed that a liter of sample water contains 1.00 mmol of Ca2+ ions and 1.50 mmol HCO3- ions. how many millimoles of CaCO3 will precipitate if this water is boiled for 15 mins?

Answer 1

.......Ca^2+ + 2HCO3^- ==> Ca(HCO3)2
I.......1.0.....1.5..........0
Which is the limiting reagent?
1 mmol Ca^2+ will form 1 mmols Ca(HCO3)2
1.5 mmol HCO3^- will form 0.75 mmols Ca(HCO3)2; therefore, 0.75 mmols Ca(HCO3)2 will be formed.

Then Ca(HCO3)2 ==> CaCO3 + H2O + CO2
0.75 mmols Ca(HCO3)2 will form 0.75 mmols CaCO3. Convert that to grams CaCO3.