# Question #6effe

##### 2 Answers

#### Explanation:

For starters, you know that **every mole** of glycerol contains

,three molesof carbon#3 xx "C"# ,eight molesof hydrogen#8 xx "H"# ,three molesof oxygen#3 xx "O"#

This means that your sample contains

#0.050 color(red)(cancel(color(black)("moles C"_3"H"_8"O"_3))) * "8 moles H"/(1color(red)(cancel(color(black)("mole C"_3"H"_8"O"_3)))) = "0.40 moles H"#

Now, in order to find the number of *atoms* of hydrogen, use the fact that **every mole** of elemental hydrogen contains **atoms** of hydrogen, as given by **Avogadro's constant**.

This means that your sample contains

#0.40 color(red)(cancel(color(black)("moles H"))) * (6.022 * 10^(23)color(white)(.)"atoms H")/(1color(red)(cancel(color(black)("mole H")))) = color(darkgreen)(ul(color(black)(2.4 * 10^(23)color(white)(.)"atoms H")))#

The answer is rounded to two **sig figs**, the number of sig figs you have for the number of moles of glycerol.

#### Explanation:

First we use Avogadro’s number to find out how many individual molecules there are. Then we multiply that value by the number of hydrogen atoms in the molecule.