Question #bfcbb

1 Answer
Stefan V.
May 19, 2017

3.8 * 10^(-21)"g"

Explanation:

Copper has a molar mass of "63.546 g mol"^(-1), which means that 1 mole of copper has a mass of "63.546 g".

Now, in order to have 1 mole of copper, you need to have 6.022 * 10^(23) atoms of copper -> this is known as Avogadro's constant.

So, right from the start, you can say that if 1 mole of copper has a mass of "63.546 g" and 1 mole of copper contains 6.022 * 10^(23) atoms of copper, then

6.022 * 10^(23)color(white)(.)"atoms Cu " -> " 63.546 g"

All you have to do now is to use this as a conversion factor to calculate the mass of 6 atoms of copper

6 color(red)(cancel(color(black)("atoms Cu"))) * "63.546 g"/(6.022 * 10^(23)color(red)(cancel(color(black)("atoms Cu")))) = color(darkgreen)(ul(color(black)(3.8 * 10^(-21)color(white)(.)"g")))

I'll leave the answer rounded to two sig figs.

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