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# How To Convert Atoms Or Molecules To Moles And Vice Versa Complete Guide With Examples

How To Convert Atoms Or Molecules To Moles

In order to convert atoms or molecules or formula units to moles OR to convert moles into atoms or molecules or formula units, we must use AVOGADRO'S number.

Avogadro's number = 6.022 *10^23 atoms or molecules or formula units per mole.

What does it mean? There are 6.022 *10^23 atoms in 1 mole. There are 6.022 *10^23 molecules in 1 mole. There are 6.022 *10^23 formula units in 1 mole.

How to convert molecules to moles? Divide by Avogadro's number

Let's take a look at an example:

Convert 500 molecules of water to moles.

500 molecules

Then, we put the units we want to cancel on the bottom and units we want to get on top.

500 molecules* moles

molecules

Now, we must use Avogadros number. There are 6.022 *10^23 molecules in 1 mole. Whenever we use Avogadro's number we will always put 1 mole in our conversion. We get:

500 molecules* _______1____mole

6.022 *10^23 molecules

We can do the same thing for atoms and formula units.

How to convert moles to molecules? Multiply by Avogadro's number

Let's take a look at an example:

Convert 4.5 moles of CH4 to moles.

4.5 moles

Then, we put the units we want to cancel on the bottom and units we want to get on top.

4.5 moles* ___________molecules

moles

Now, we must use Avogadros number. There are 6.022 *10^23 molecules in 1 mole. Whenever we use Avogadro's number we will always put 1 mole in our conversion. We get:

4.5 moles* 6.022 *10^23 molecules

1 mole

Let's try a more advanced problem:

How many hydrogen atoms are in 50 moles of H2O?

50 moles H2O

Then, we put the units we want to cancel on the bottom and units we want to get on top.

50 moles H2O* ___________molecules

moles

Now, we must use Avogadros number. There are 6.022 *10^23 molecules in 1 mole. Whenever we use Avogadro's number we will always put 1 mole in our conversion. We get:

50 moles H2O* 6.022 *10^23 molecules of H2O

1 mole

But we need H atoms! There are 2 hydrogen atoms in 1 H2O molecule.

50 moles H2O* 6.022 *10^23 molecules of H2O * 2H atoms

1 mole of H2O 1 molecule H2O