Charge of Electrons in a Copper Sample

Problem Statement

There are approximately $2.85\times 10^{22}$ copper atoms in a 3.00 g sample. What is the total charge of all of the electrons in the sample?

I Need a Hint!

Each copper atom has 29 electrons.

Solution

Each copper atom has 29 electrons, and the charge on a single electron is $1.602\times 10^{-19}C$. Thus, the total charge of the electrons in the copper sample is:

$$Q=\left(2.85\times 10^{22}atoms\right)\left(\frac{29e^{-}}{1atom}\right)\left(\frac{1.602\times 10^{-19}C}{1e^{-}}\right)$$ $$Q=1.32\times 10^{5}C$$