# Question #a0144

##### 1 Answer

#### Answer:

#### Explanation:

To find the number of atoms of copper you have in **320 g** of copper, you first need to find out how many *moles* of copper you have.

Once you get the number of moles you have in 320 g of copper, you can use its *molar mass* to find the number of atoms.

An element's molar mass simply tells you what the mass of **one mole** of that element is.

In copper's case, its molar mass is equal to *every mole* of copper has a mass of

The number of moles of copper you have is

#320color(red)(cancel(color(black)("g"))) * "1 mole Cu"/(63.546color(red)(cancel(color(black)("g")))) = "5.036 moles Cu"#

Now, use the fact that *one mole* of any element contains exactly **Avogadro's number**.

In your case, **5.036 moles** would contain

#5.036color(red)(cancel(color(black)("moles Cu"))) * (6.022 * 10^(23)"atoms of Cu")/(1color(red)(cancel(color(black)("mole Cu")))) = color(green)(3.0 * 10^(24)"atoms of Cu")#

The answer is rounded to two sig figs.