[millerst]

Hello, I have a question that I'm not sure how to answer.

The reaction of iron (III) oxide with powdered aluminum is known as the thermite reaction.
     2Al + Fe₂O₃ -->  A₂O₃ + 2Fe

(a) Calculate the mass of aluminum oxide, Al₂O₃, that is produced when 1.42 x 10²⁴ atoms of Al react with Fe₂O₃.


My first insticts were to set up the ratio.

2 : 1 : 1 :2

Now I'm not sure how I go about the next part. Which of the compounds am I finding the molar mass for?

Al₂O₃ has a molar mass of 102 g/mol.
Al has a molar mass of 27 g/mol.
Fe₂O₃ has a molar mass of 160 g/mol.

Al₂O₃                 ** Must convert this to moles.
= 1.42 x 10²⁴ atoms


Could someone help me through this problem?

Thanks,
Stefan

[Rich2189]

You missed the l off Aluminium in Aluminium Oxide in your equation

Fe₂O_3(s) + 2Al_(s) --->  Al₂O_3(s) + 2Fe_(l)

Right since you had a go at the calculation I'm willing to help you.

1. You must work out the number of moles of Aluminium you have.

2. Due to the ratio you correctly pointed out 2 moles of aluminium react to produce 1 mole of Aluminium Oxide

3. Apply the ratio to work out the number of moles of Aluminium oxide you must get from however many moles of Aluminium you had.

4. Multiply the mass of 1 mole of aluminium oxide by the number of moles you worked out in step 3.

[AWK]

Al2O3                 ** Must convert this to moles.
= 1.42 x 1024 atoms

to moles of Al, of course,

then to moles of Al2O3,

then to mass of Al2O3.

That's all