Question

How many atoms are there in 2.0 mole of Si?

Answer 1

Well how many eggs in two dozen eggs?

Explanation:

And this is PRECISELY the same sort of question as you asked....

One mole specifies `"Avogadro's number"` of particles...i.e. `N_A=6.022xx10^23*mol^-1`. Why do we use such an absurdly large number? Because `"Avogadro's number"` of `""^12C` atoms, has a MASS of `12.0*g` PRECISELY.

`"Avogadro's number"` is thus the link between micro world atoms, and molecules, the which we cannot see but whose existence we can infer, with the macro world of grams, and litres, and kilograms, that which we can measure by some means in a laboratory.

And so we got a `2*mol` quantity of silicon atoms....i.e. we gots..

`2.0*molxx6.022xx10^23*mol^-1=12.022xx10^23*"silicon atoms"`.

And what is the mass of this molar quantity?

Answer 2

`~~1.2*10^24` atoms

Explanation:

In one mole of atoms, there exists approximately `6.02*10^23` atoms.

So, in `2` moles of silicon atoms, there will be around

`2*6.02*10^23~~1.2*10^24` silicon atoms.