# Question #eb525

##### 1 Answer

#### Explanation:

I assume that you're interested in finding out how may **atoms** of sodium,

The first thing to do here is convert the mass of sodium from *kilograms* to *grams*

#0.1 color(red)(cancel(color(black)("kg"))) * (10^3"g")/(1color(red)(cancel(color(black)("kg")))) = "100 g"#

From this point on, you will have to use two *conversion factors*

gramstomoles#-># use themolar massof sodium#" "color(blue)((1))# molestonumber of atoms#-># useAvogadro's number#" "color(darkgreen)((2))#

**Grams** to **moles**

The **molar mass** of an element essentially tells you the mass of **one mole** of said element. In this case, sodium has a molar mass of **one mole** of sodium has a mass of

In your case,

#100color(blue)(cancel(color(black)("g"))) * "1 mole Na"/(23.0color(blue)(cancel(color(black)("g")))) = "4.35 moles Na"#

**Moles** to **number of atoms**

A **mole** is simply a very, very large collection of atoms. In order to have **one mole** of a given element, you need to have **atoms** of said element.

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

In your case, **moles** of sodium will contain

#4.35 color(darkgreen)(cancel(color(black)("moles Na"))) * (6.022 * 10^(23)"atoms of Na")/(1color(darkgreen)(cancel(color(black)("moles Na")))) = color(green)(|bar(ul(color(white)(a/a)color(black)(2.6 * 10^(24)"atoms Na")color(white)(a/a)|)))#

I'll leave the answer rounded to two **sig figs**, but keep in mind that you only have one sig fig for the mass of sodium.