Question

how many formula units are in 5.5 moles of mgo? ?×10? formula units of mgo

Explanation:

Step1: Recall Avogadro's number

1 mole of any substance contains $6.022\times 10^{23}$ formula - units (or molecules for covalent compounds).

Step2: Calculate formula - units

To find the number of formula - units in 5.5 moles of MgO, we multiply the number of moles by Avogadro's number. Let $N$ be the number of formula - units, $n = 5.5$ moles, and $N_A=6.022\times 10^{23}$ formula - units/mol. Then $N=n\times N_A$.
$N = 5.5\times6.022\times 10^{23}$
$N=(5.5\times6.022)\times 10^{23}$
$N = 33.121\times 10^{23}$
In scientific notation, $N = 3.3121\times 10^{24}$ formula - units.

Answer:

$3.3121\times 10^{24}$ formula units of MgO