Question

Question #07ab7

Answer 1

`5.8 * 10^(21)`

Explanation:

Your tool of choice here is Avogadro's constant, which acts as the definition of a mole.

In order to have `1` mole of sodium oxide, you need to have `6.022 * 10^(23)` formula units of sodium oxide `->` this is known as Avogadro's constant.

`color(blue)(ul(color(black)("1 mole Na"_2"O" = 6.022 * 10^(23)color(white)(.)"formula units Na"_2"O")))`

So if you know for a fact that `1` mole of sodium oxide contains `6.022 * 10^(23)` formula units of sodium oxide, you can say that your sample will contain

`9.7 * 10^(-3)color(red)(cancel(color(black)("moles Na"_2"O"))) * (6.022 * 10^(23)color(white)(.)"formula units Na"_2"O")/(1color(red)(cancel(color(black)("mole Na"_2"O"))))`

`= color(darkgreen)(ul(color(black)(5.8 * 10^(21)color(white)(.)"formula units Na"_2"O")))`

The answer is rounded to two sig figs, the number of sig figs you have for the number of moles present in the sample.