Since I'm really bad at analytical chemistry and especially at practical work in laboratory I came across a problem regarding the determination of calcium in a sample of calcium salt. We precipitated calcium ions in a sample with ammonium oxalate and then we solubilized it in sulfuric acid. We titrated the oxalate in this solution with KMnO4
The problem is that I have to write down some equations and I'm not quite sure I wrote down the right ones.
First I have to write down the equation for reaction between Ca2+
and ammonium oxalate. My idea: Ca2+
(Am I missing something? We also added the indicator methyl red and NH3
The second is the equation for reaction of solubilization of calcium oxalate in sulfuric acid. I don't have any ideas what to write.
The last one is a reaction of oxalate in KMnO4
in acid environment. I'm sure for this one, so I won't bother you with it.
I'd really appreciated if someone could write down these two equations, because it's important I get it right, 'cause I have to make some calculations afterwards and (of course) I need the right stoichiometry. I have to calculate how much calcium was in our sample.
Oh, and I apologize if my english isn't so good. I sometimes have problems, especially with chemical expressions.