Question #fa66b

1 Answer
Apr 7, 2017

Answer:

#1.76 * 10^(25)#

Explanation:

For starters, you know that #1# mole of boron trifluoride contains

  • one mole of boron, #1 xx "B"#
  • three moles of fluorine, #3 xx "F"#

This implies that your sample of boron trifluoride will contain

#9.72 color(red)(cancel(color(black)("moles BF"_3))) * "3 moles F"/(1color(red)(cancel(color(black)("mole BF"_3)))) = "29.16 moles F"#

Now, #1# mole of any element contains #6.022 * 10^(23)# atoms of that element #-># this is known as Avogadro's constant.

You can thus say that your sample will contain

#29.16 color(red)(cancel(color(black)("moles F"))) * (6.022 * 10^(23)color(white)(.)"atoms of F")/(1color(red)(cancel(color(black)("mole F")))) = color(darkgreen)(ul(color(black)(1.76 * 10^(25)color(white)(.)"atomf of F")))#

The answer is rounded to three sig figs, the number of sig figs you have for the number of moles of boron trifluoride.