Question

Calculate mass of iron, which will be converted into (Fe3O4) by the action of 18g of steam on it.

Answer 1

Write and balance the equation.
Convert 18 g steam to mols. mols = grams/molar mass
Using the coefficients in the balanced equation, convert mols H2O to mols Fe.
Now convert mols Fe to grams Fe. g = mols Fe x atomic mass Fe.

Answer 2

First we write the balanced chemical reaction involved:
3Fe + 4H2O -> Fe3O4 + 4H2
Since we have 18 g of steam, we have to convert this to moles and use the stoich ratios from the reaction to get amount of Fe needed to react with it. To convert mass to moles, we get the molecular weight (MW) of the substance (just get a periodic table and add the individual weights of elements in the chemical formula). Thus,
MW of H2O = 2*1 + 16 = 18 g/mol
MW of Fe = 55.85 g/mol
From the reaction, we can see that for every 4 moles of H2O reacted, 3 moles of Fe are also consumed. Therefore,
18 g * (1 mol H2O / 18 g) * (3 mol Fe / 4 mol H2O) * (55.85 g / mol Fe)
= 41.89 g Fe

Hope this helps~ :3

Answer 3

42g

Answer 4

First we write the balanced chemical reaction involved:
3Fe + 4H2O -> Fe3O4 + 4H2
Since we have 18 g of steam, we have to convert this to moles and use the stoich ratios from the reaction to get amount of Fe needed to react with it. To convert mass to moles, we get the molecular weight (MW) of the substance (just get a periodic table and add the individual weights of elements in the chemical formula). Thus,
MW of H2O = 2*1 + 16 = 18 g/mol
MW of Fe = 55.85 g/mol
From the reaction, we can see that for every 4 moles of H2O reacted, 3 moles of Fe are also consumed. Therefore,
18 g * (1 mol H2O / 18 g) * (3 mol Fe / 4 mol H2O) * (55.85 g / mol Fe)
= 41.89 g Fe