# How many oxygen atoms are represented by MgSO_4 * 7H_2O?

Dec 20, 2015

$11$

#### Explanation:

In ${\text{MgSO}}_{4}$, the number of oxygen atoms is represented by the subscript directly next to the $\text{O}$.

In $\text{7H"_2"O}$, the coefficient $7$ can be multiplied throughout each element in the molecule.

$\text{MgS"color(red)("O"_4)rarr"4 O atoms}$

color(red)("7")"H"_2color(red)("O")rarr"7 O atoms"

There is a total of $4 + 7 = 11$ oxygen atoms.