Question

Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid fuel rocket motors. The reaction isFe2O3(s) + 2Al(s) → 2Fe(l) + Al2O3(s)

Answer 1

1) Balance the chemical reaction.

`Fe_2O_(3(s))+2Al_((s))\rightarrow2Fe_((l))+Al_2O_(3(s))`

2) List the known and unknown quantities.

Product: Iron (Fe).

Mass: 64.37 g.

Molecular mass: 55.845 g/mol.

Reactant: Aluminum (Al).

Mass: unknown.

Molecular mass: 26.982 g/mol.

3) Convert the mass of Fe to moles of Fe.

`mol\text{ }Fe=64.37\text{ }g\text{ }Fe*\frac{1\text{ }mol\text{ }Fe}{55.845\text{ }g\text{ }Fe}=1.15265\text{ }mol\text{ }Fe`

4) Convert moles of Fe to moles of Al

The molar ratio between Fe and Al is 2 mol Fe: 2 mol Al.

`mol\text{ }Al=1.15265\text{ }mol\text{ }Fe*\frac{2\text{ }mol\text{ }Al}{2\text{ }mol\text{ }Fe}=1.15265\text{ }mol\text{ }Al`

5) Convert moles of Al to mass of Al.

`g\text{ }Al=1.15265\text{ }mol\text{ }Al*\frac{26.982\text{ }g\text{ }Al}{1\text{ }mol\text{ }Al}=31.10080\text{ }g\text{ }Al`

The mass of Aluminum that must be used is 31.10 g Al.

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