Calculate Rust Removal from a Bathtub via Oxalic Acid: 20.7g

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Oxalic acid, found in spinach, is effective for rust removal, particularly from bathtub rings. The chemical reaction involves oxalic acid reacting with rust (Fe2O3) to produce iron and other byproducts. A calculation using a 0.370 M solution of oxalic acid reveals that 500 mL yields 0.185 moles of oxalic acid. This translates to the potential removal of 20.7 grams of iron. However, the focus should be on the mass of rust (Fe2O3) removed, as one mole of oxalic acid corresponds to one mole of rust. Therefore, the correct approach is to calculate the mass of Fe2O3 instead of iron to determine the actual amount of rust that can be eliminated.
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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 anyone 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 ©)
 
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