Question

How many silver atoms are there in a `0.566*kg` mass of silver?

Answer 1

`0.566*kg` of silver `~=` `30xx10^23" silver atoms"`

Explanation:

We know (or should know) that the formula mass of silver is `107.87*g*mol^-1`. How did I know this? Did I know it off the top of my head? How will you know this if you are asked the question in an exam?

Now `1` `"mole"` of silver atoms or in a `107.87*g` mass, there are, by definition, `6.022xx10^23` `"individual atoms of silver."`

So all I have to do to get the number of silver atoms, is (i) calculate the molar quantity, and (ii) multiply this molar quantity by `6.022xx10^23*mol^-1`, i.e. `"Avogadro's number"`.

So.......

`(0.566xx10^3*g)/(107.87*g*mol^-1)` `=` `5.25*mol`.

And `5.25*molxx6.022xx10^23*mol^-1` `~=` `30xx10^23" silver atoms"`