Titration, finding percentage of compound in unknown substance
A .750 g sample of an uknown solid is dissolved in 100 mL of water and acidified with 25 mL of 3 M H2SO4 then titrated with a .0200 M KMn04 solution. If the unknown solid requires 12.5 mL of the KMnO4 solution to reach the endpoint, what is the % sodium oxalate in the unknown solid? Assume the only compound in the unknown solid that reacts with the KMnO4 solution is sodium oxalate. Report your answer as a percentage.
Can someone please help?? i can't figure this one out! I'm not even sure where to begin. If someone could explain how to start I think I could figure out the rest.
You need to start with a balanced equation. To check myself, I googled it and found this:
2 MnO4- + 16 H+ + 5 C2O42- -----10e-----> 2 Mn+2 + 8 H2O + 10 CO2 (g)
Next you need to find the moles of permanganate:
moles of permanganate* = .0125L x .0200 M
Next find the moles of oxalate by using the coefficients in the balanced equation to set up a proportion:
5 moles oxalate / 2 moles permanganate = x moles oxalate / moles of permanganate*
Solve for x moles of oxalate
Now find the mass of the sodium oxalate = moles of oxalate x molar mass of Na2C2O4
% = part / whole x 100 so in this case
% sodium oxalate = mass of sodium oxalate* / .750 g x 100
Hope that helps!