Question

How many moles of `"Al"` are needed to form `3.7` moles of `"Al"_2"O"_3`?

`4"Al" + 3"O"_2 -> 2"Al"_2"O"_3`

Answer 1

`"7.4 mol Al"`

Explanation:

The balanced chemical equation for it is

`4Al + 3O_2 -> 2Al_2O_3`

You have `3.7` moles of `Al_2O_3`. When you balanced the equation, you got `2` moles of `"Al_2O_3` and `4` moles of `Al`, so

"4 mol `Al` gives `2` mol `Al_2O_3`

After you cancel out the units of measurement to check the order of the conversion, multiply `3.7` with `4` and then divide the answer by `2`. You get `7.4` moles of `Al`.