# How many atoms are in 1 mole of Na_3PO_4?

Mar 5, 2016

$5 \cdot {10}^{24} \text{atoms}$

#### Explanation:

In order to figure out how many atoms you get per mole of sodium triphosphate, ${\text{Na"_3"PO}}_{4}$, you must use the fact that one mole of any substance contains $6.022 \cdot {10}^{23}$ atoms, molecules, or formula units of that substance.

This is known as Avogadro's number.

Since you're dealing with an ionic compound, one mole of sodium triphosphate will contain $6.022 \cdot {10}^{23}$ formula units of sodium triphosphate.

Now, how many atoms do you get per formula unit of sodium triphosphate?

As you can see by examining the chemical formula, one formula unit contains

• three atoms of sodium $\to 3 \times \text{Na}$
• one atom of phosphorus $\to 1 \times \text{P}$
• four atoms of oxygen $\to 4 \times \text{O}$

This means that one formula unit will contain a total of

$3 \times \text{Na" + 1 xx "P" + 4 xx "O" = "8 atoms}$

Therefore, one mole of formula units will contain

6.022 * 10^(23)color(red)(cancel(color(black)("formula units"))) * "8 atoms"/(1color(red)(cancel(color(black)("formula unit")))) = 4.82 * 10^(24)"atoms"

You should round this off to one sig fig, the number of sig figs you have in $1$ mole, to get

"no. of atoms" = color(green)(| bar(ul(5 * 10^(24)"atoms"))|)