posted by kay on .
For a lab in school we had to mix together sodium carbonate and calcium chloride and had that go through a filter, finally ending with our final product of calcium carbonate (chalk), my question is that we have to do a graph and the graph shows that as the mass of calcium chloride increases, the mass of the calcium carbonate stays nearly the same (plateau's) WHY IS THAT?
Ca^2+(aq) + CO3^2-(aq) ==> CaCO3(s)
The net ionic equation is shown above. As the Ca^2+ is increased it reacts with carbonate ion and the CaCO3 is increased. At some point, the last of the carbonate is gone (since none is being added); therefore, no matter how much more Ca^2+ is added (from CaCl2), no more CaCO3 can be produced.