Question #fa66b

1 Answer
Stefan V.
Apr 7, 2017

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.

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