Question

How many formula units in `5.88*mol` of `CaO_2`?

Answer 1

Well how many eggs in 5 dozen eggs.........? And you mean on `CaO` not `CaO_2`.

Explanation:

The given question is precisely the same as that I asked in the opening, except that here I deal with MOLES not DOZENS.....

See here for a similar treatment.

`1*mol` of stuff unequivocally specifies `6.022xx10^23` individual items of that stuff, where `6.022xx10^23` is Old Avogadro's number, symbolized by `N_A`.

Now in each formula unit of `CaO`, there are TWO atoms.......

And so..................

`"number of atoms"-=2*"atoms"xx6.022xx10^23*mol^-1xx5.88*mol~=30*N_A`

What is the mass of this quantity of `CaO`?

Answer 2

A `5.88` mole sample of `"CaO"` contains `3.54xx10^24` formula units of `"CaO"`.

Explanation:

There is no compound with the formula `"Ca"_2"O"`. The formula for calcium oxide is `"CaO"`. One mole of anything is `6.022xx10^23` of anything, including formula units. In order to determine the number of formula units in a `5.88` mole sample of `"CaO"`, multiply the given moles by `6.022xx10^23` formula units/mol#.

`5.88color(red)cancel(color(black)("mol CaO"))xx(6.022xx10^23 "formula units CaO")/(1color(red)cancel(color(black)("mol CaO")))=3.54xx10^24" formula units of CaO"`

Thanks to anor77.