Half Equations and the Thermite Process for Welding Railway Tracks

  • Thread starter rosie_burk
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In summary, the thermite process is a method of welding railway tracks together by using a redox reaction between aluminium powder and iron(iii) oxide to form molten iron. The half equation for the conversion of iron(iii) oxide to metallic iron is Fe2O3(s) + 6e- --> 2Fe(l) + 3O2-(s). The overall equation for the thermite process is 2Al(s) + Fe2O3(s) --> 2Fe(l) + Al2O3(s).
  • #1
rosie_burk
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The thermite process can be used to weld lengths of railway track together. A mould placed over the ends of the rails to be joined is filled with a charge of aluminium powder and iron(iii) oxide. When the mixture is ignited, a redox reaction occurs to form molten iron, which joins the rails together.

a. Write a half equation for the conversion of iron(iii) oxide to metallic iron.

i got Fe2O3 + 6H+ +6e- = 2Fe + 3H20- but that's wrong according to the book, the answer is Fe2O3(s) + 6e- --> 2Fe(l) + 3O 2- (s). I don't understand why they balanced it using oxygen instead of water.

b. Write the overall equation for the thermite process.
 
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  • #2
rosie_burk said:
The thermite process can be used to weld lengths of railway track together. A mould placed over the ends of the rails to be joined is filled with a charge of aluminium powder and iron(iii) oxide. When the mixture is ignited, a redox reaction occurs to form molten iron, which joins the rails together.

a. Write a half equation for the conversion of iron(iii) oxide to metallic iron.

i got Fe2O3 + 6H+ +6e- = 2Fe + 3H20- but that's wrong according to the book, the answer is Fe2O3(s) + 6e- --> 2Fe(l) + 3O 2- (s). I don't understand why they balanced it using oxygen instead of water.

Because that would be two half reactions...

6H+ + 3O-2 ------> 3H2O

and

Fe2O3 + 6e- -------------> 2Fe(0) + 3O-2
 

Related to Half Equations and the Thermite Process for Welding Railway Tracks

1. What is a half equation?

A half equation is a chemical equation that shows the oxidation or reduction reaction of a single reactant. It only includes the reactant and the products involved in the electron transfer process.

2. How is a half equation different from a normal chemical equation?

A normal chemical equation shows the overall reaction that occurs between multiple reactants and products. A half equation, on the other hand, only shows the electron transfer process of a single reactant.

3. What is the purpose of writing a half equation?

Writing a half equation allows for a clearer understanding of the electron transfer process that occurs in a redox reaction. It also helps in balancing the overall reaction and determining the oxidation state of the reactant.

4. Can a half equation exist on its own?

No, a half equation is always paired with another half equation to form a complete redox reaction. This is because oxidation and reduction reactions always occur simultaneously.

5. How do you balance a half equation?

To balance a half equation, the number of atoms on both sides of the equation must be equal. This is done by adding appropriate coefficients to the reactant and product molecules. The number of atoms and charges must also be balanced for both the reactant and product side.

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