# How many moles of nitrogen, #N_2#, are there in #4.3*10^23# #N_2# molecules?

##### 1 Answer

#### Explanation:

In order to figure out how many *moles* of nitrogen gas would contain that many molecules, you need to know how many molecules of a substance are needed in order to make **one mole**.

If you know how many molecules of a substance you get in **one mole**, you can use this as a **conversion factor** to help you find the answer.

The number of molecules that are needed in order to have **one mole** of a substance is known as **Avogadro's number** and is equal to

#color(blue)(|bar(ul(color(white)(a/a)"1 mole" = 6.022 * 10^(23)"molecules"color(white)(a/a)|))) -># Avogadro's number

This is true *regardless* of the substance you're dealing with. Simply put, in order to have a mole of *anything*, you need to have *anything*.

Use Avogadro's number as a conversion factor to get

#4.3 * 10^(23)color(red)(cancel(color(black)("molec. N"_2))) * overbrace("1 mole N"_2/(6.022 * 10^(23)color(red)(cancel(color(black)("molec. N"_2)))))^(color(purple)("Avogadro's number")) = "0.71405 moles N"_2#

Rounded to two **sig figs**, the number of sig figs you have for the number of molecules of nitrogen, the answer will be

#"no. of moles N"_2 = color(green)(|bar(ul(color(white)(a/a)0.71color(white)(a/a)|)))#