Question #bfcbb

1 Answer
May 19, 2017

3.8 * 10^(-21)"g"3.81021g

Explanation:

Copper has a molar mass of "63.546 g mol"^(-1)63.546 g mol1, which means that 11 mole of copper has a mass of "63.546 g"63.546 g.

Now, in order to have 11 mole of copper, you need to have 6.022 * 10^(23)6.0221023 atoms of copper -> this is known as Avogadro's constant.

So, right from the start, you can say that if 11 mole of copper has a mass of "63.546 g"63.546 g and 11 mole of copper contains 6.022 * 10^(23)6.0221023 atoms of copper, then

6.022 * 10^(23)color(white)(.)"atoms Cu " -> " 63.546 g"6.0221023.atoms Cu 63.546 g

All you have to do now is to use this as a conversion factor to calculate the mass of 66 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.