# When steam (hot water) is passed over iron, hydrogen gas and iron (lll) oxide are formed. What mass of steam would be needed to react completely with 100.0 g of iron?

Mar 7, 2016

The reaction requires 48.4 g of steam.

#### Explanation:

Step 1. Write the balanced equation.

${\text{2Fe" + "3H"_2"O" → "Fe"_2"O"_3 + "3H}}_{2}$

Step 2. Calculate the moles of iron.

100 cancel("g Fe") × "1 mol Fe"/(55.84 cancel("g Fe")) = "1.791 mol Fe"

Step 3. Calculate the moles of $\text{H"_2"O}$.

1.791 cancel("mol Fe") × ("3 mol H"_2"O")/(2 cancel("mol Fe")) = "2.686 mol H"_2"O"

Step 4. Calculate the mass of $\text{H"_2"O}$.

2.686 cancel("mol H"_2"O") × ("18.02 g H"_2"O")/(1 cancel("mol H_2"O"")) = "48.4 g H"_2"O"
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