# How many atoms or molecules are present in 1.0 mol of Au? How am I able to find the answer?

##### 1 Answer
May 11, 2015

You use the fact that 1 mole of any substance contains exactly $6.022 \cdot {10}^{23}$ atoms or molecules of that substance - this is known as Avogadro's number.

In your case, 1 mole of gold will have exactly $6.022 \cdot {10}^{23}$ atoms of gold.

1.0cancel("mole") * (6.022 * 10^(23)"atoms")/(1cancel("mole")) = 6.022 * 10^(23)"atoms of Au"

If round the answer to two sig figs, the number of sig figs in 1.0, you'll get

"1.0 mole Au" = color(green)(6.0 * 10^(23)"atoms Au")

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video from: Noel Pauller

And here is an advanced example...

video from: Noel Pauller