## Volumetric Analysis

1. A useful application of oxalic acid (found in spinach as well as instigates the formation of kidney stones) is for the removal of rust
from bathtub rings via the following quantitatively correct equation: .

4 H (aq) + Fe2 03(S)+ C2 H2 04(aq) 2 Fe(aq)+ C2 04(aq) + 3 H2 0 (1)

Calculate the mass in grams of rust that may be removed from a ring ridden bathtub via the application of 500 mL of a
0.370 M solution of oxalic acid.

For this problem I 500x10^3 L C2H204 x .37 mol C2H2O4/i L c2h2o4 = .185 mol C2H2O4

then I .185 C2H2O4 x 2 mol Fe/ a mol C2H2O4 x 55.84 g Fe / mol Fe = 20.7 grams of Fe

this seems right to me but at the same time I'm still kind of 'rusty' with chemistry and I wanted to see if any one knew if this was correct and if it is wrong oculd lead me in the right direction?
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 The only thing that does not seem right to me is that you have calculated the mass of iron on the right hand side of the equation. The question asks how much rust can be removed so you want to work out the mass of the Fe2O3 that is removed. One mole of rust can be removed by one mole of oxalic acid so you are almost right. The Bob (2004 ©)