Question

When 0.848 grams of finely divided iron is burn, 1.212 grams of reddish brown oxide is obtained. Write a balanced chemical equation for the reaction of iron andmolecular oxygen based on the empirical formula.

Answer 1

The kind of reaction involved is combination reaction.

Fe + O2 -----> FexOy

Since we're given the mass of the reddish brown oxide (1.212g), we can calculate for the amount of oxygen gas used by substracting the amount of iron from the mass of the product:

grams O2 = (grams product) - (grams Fe)

= 1.212 g - 0.848 g

= 0.364 g O2

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We can determine the empirical formula by getting the ratio of the moles of the reactants:

First, convert the mass of reactants into moles:

Then get the ratio of the moles:

Fe:

O:

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We can now write

FexOy as Fe1.33O1

But we have to multiply the whole formula by 3 to obtain whole number ratio

[ Fe1.33O1]3 = Fe4O3

Hence, the balanced equation is:

8Fe + 3O2 ------> 2Fe4O3

Answer 2

Since the empirical formula for the oxide is Fe2O3:

The balanced equation is:

4 Fe(s) + 3 O2(g) => 2 Fe2O3(s)