Question #6effe

2 Answers
Jun 17, 2017

Answer:

#2.4 * 10^(23)#

Explanation:

For starters, you know that every mole of glycerol contains

  • three moles of carbon, #3 xx "C"#
  • eight moles of hydrogen, #8 xx "H"#
  • three moles of 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 #6.022 * 10^(23)# 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.

Jun 18, 2017

Answer:

#2.41 xx 10^23#

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.

#0.050mol * 6.022 xx 10^23 ("units"/"mol") = 3.011 xx 10^22# molecules

#3.011 xx 10^22 "molecules" * 8 ((H "atom")/"molecule") = 2.41 xx 10^23# hydrogen atoms