4
$\begingroup$

My class just did a lab today where we mixed cobalt oxalate with $40~\mathrm{mL}$ of $\ce{H2SO4}$ and then titrated it with $\ce{KMnO4}$ (potassium permanganate). I need the mole ratio of cobalt oxalate and $\ce{KMnO4}$ and am not sure how to set up the equation. She provided us with this formula with 3 variables A,B,C - Co(a)(C2O4)(b) * (c)H2O but I am not sure what to do with it. I am also confused as cobalt oxalate appears as $\ce{CoC2O4}$ in her equation yet Google says it's $\ce{H2C2CoO6}$.

My table in my lab book is asking me for "Moles Oxalate Present" , "Mass of Oxalate in Sample" , and "Percent Mass of Oxalate in Sample (%)". It is also referring to the "Mass of transition metal oxalate used" which we took during the actual lab. (I guess this lets me know that it solely wants oxalate and to calculate these values aside from cobalt oxalate?)

I am very confused and if any part of this question needs to be cleared up I can certainly do so.

I can provide any/all data that I took during the lab, but explaining conceptually will still do me some good here. I really just don't know where to start with all this data.

My book also gave me this formula for the reaction of oxalate ions with permanganate ions:

$$\ce{5C2O4^{2-} + 2MnO4- + 16H+ -> 10CO2 + 2Mn^{2+} + 8H2O}$$

Will this factor at all into my calculations?

$\endgroup$
  • $\begingroup$ For starters, the Google oxalate must be wrong. It can technically be either $\ce{H4C2CoO6}$ or $\ce{H2C2CoO5}$, but a random search just gave the former. Do you notice an easy way to turn your teacher's formula into the corrected Google formula(e)? The equation you have written at the bottom will most certainly factor in, by the way; and to solve this problem, we need a minimum of three more values (or two values and one bit of information). $\endgroup$ – Jan Jun 23 '15 at 0:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.