Question

How to calculate number of atoms of copper present in 19.7g of 22carat gold?

Answer 1

1000gm gold have 84 gms of Copper.

So, 1gm gold have 0.084gm of Copper.

Therefore, 19.7 gm of gold comtains 19.7×0.084 gm of copper.

That is 1.654 gm of copper.

1 mol of coper weighs 63.5 gm and have Avogrado number of atoms.

So 1gm copper have Na/63.5 number of atoms.


Therefore, 1.654gm of copper have(Na×1.654)/63.5 number of atoms.

The answer is
1.654Na/63.5