# Question #6c787

##### 1 Answer

Here's how you can approach such problems.

#### Explanation:

The question asks you determine what the mass of a large group of iron atoms, *individual* iron atom has a mass of **56 u**.

Now, they tell you that *each of those atoms* has a mass of **56 u**. The symbol "u" is used to denote the equivalent of

In more practical terms,

Since each atom of iron weighs **56 times more** than that, you have

Each iron atom has a mass of

An interesting thing to notice here is that if you use the number of atoms present in **1 mole** of iron, and multiply this number by the mass of an individual iron atom, you'll get the **molar mass** of iron.

By definition, **one mole** of any substance contains exactly **Avogadro's number**.

In your case, one mole of iron would have a mass of

If you take into account rounding and sig figs, this result matches the actual molar mass of iron, which is **55.845 g**.

So remember, one "u" is always equal to