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

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In summary, the conversation is discussing the use of oxalic acid for removing rust from bathtubs. The equation for this reaction is given and the question asks for the mass of rust that can be removed using a certain amount of oxalic acid solution. The correct answer involves converting the volume of the solution to moles of oxalic acid, then using the mole ratio to calculate moles of rust and finally converting to grams. However, the calculation in the conversation is slightly incorrect as it calculates the mass of iron instead of rust.
  • #1
Addie
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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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  • #2
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 ©)
 
  • #3


Your calculations are correct! To check your work, we can use dimensional analysis to make sure the units cancel out correctly. Starting with 500 mL of the oxalic acid solution, we can convert to moles of oxalic acid:

500 mL x (1 L / 1000 mL) x (0.370 mol / 1 L) = 0.185 mol C2H2O4

Then, using the balanced equation, we can convert moles of oxalic acid to moles of iron (Fe):

0.185 mol C2H2O4 x (2 mol Fe / 1 mol C2H2O4) = 0.37 mol Fe

Finally, we can convert moles of iron to grams of iron:

0.37 mol Fe x (55.84 g Fe / 1 mol Fe) = 20.7 g Fe

Therefore, your answer of 20.7 grams of iron is correct. Keep up the good work!
 

1. How does oxalic acid remove rust from a bathtub?

Oxalic acid is a strong acid that reacts with the iron oxide present in rust. This reaction breaks down the rust molecules, making it easier to remove from the surface of the bathtub.

2. Is oxalic acid safe to use for rust removal?

Oxalic acid can be harmful if not used properly. It is important to follow all safety precautions, such as wearing protective gear and using it in a well-ventilated area. It is also recommended to dilute the acid with water before using it on a bathtub.

3. How much oxalic acid should be used to remove rust from a bathtub?

The recommended amount of oxalic acid for rust removal from a bathtub is 20.7g. This amount may vary depending on the severity of the rust and the size of the bathtub.

4. Can oxalic acid damage the bathtub surface?

Oxalic acid is a strong acid and may damage certain surfaces, such as marble or granite. It is important to test a small area before using it on the entire bathtub. It is also recommended to rinse the bathtub thoroughly after using oxalic acid to avoid any potential damage.

5. Are there any alternatives to using oxalic acid for rust removal?

Yes, there are alternative methods for removing rust from a bathtub, such as using a mixture of baking soda and vinegar or using a commercial rust remover. It is important to carefully follow the instructions for any alternative method and to test a small area before using it on the entire bathtub.

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