# What is the mass of 4.50 mol Fe?

May 1, 2016

#### Answer:

Elemental iron has a molar mass of $55.85$ $g \cdot m o {l}^{-} 1$

#### Explanation:

So the mass of the given molar quantity?

$4.50 \cdot m o l \times 55.85 \cdot g \cdot m o {l}^{-} 1$ $\approx$ $250 \cdot g$

May 1, 2016

#### Answer:

4.50 moles $\times$ molar mass of Fe
4.50 $\times$ 55.9 = ?

#### Explanation:

Assume that:
n - number of moles
m - mass of substance
M - molar mass (same as atomic weight on periodic table)
$n = m \div M$

4.50 moles (n) has been given to you.

Now find the molar mass (M) of Fe. If you look into your periodic table, the molar mass of Fe is 55.9 g/mol.

To find the mass of substance (m), you need to flip over the formula, therefore, $m = M \times n$
The mass (m) of Fe is:
[55.9 g/mol $\times$ 4.50 moles] = 251.6 grams.
Note: It is rounded to the nearest one decimal place.

4.50 moles of Fe should give you 251.6 grams of Fe.