Question

Question #6cb30

Answer 1

You'd need `"20.9 g"` of iron to react with that much oxygen.

Start by taking a look at your balanced chemical equation

`3Fe + 2O_2 -> Fe_3O_4`

Notice that you have a `"3:2"` mole ratio between iron and oxygen - this represents the ratio according to which iron and oxygen will mix to form the product, `Fe_3O_4` (commonly known as magnetite).

So, for every 3 moles of iron, you need 2 moles of oxygen for the reaction to take place. You can determine the number of moles of oxygen by using its molar mass

`"8.0 g oxygen" * "1 mole"/"32.0 g" = "0.250 moles oxygen"`

This much oxygen will need

`"0.250 moles oxygen" * "3 moles iron"/"2 moles oxygen" = "0.375 moles iron"`

Using iron's molar mass to determine how many grams are needed will produce

`"0.375 moles iron" * "55.85 g"/"1 mole" = "20.9 g iron"`