# What is the gram-formula mass of (NH_4)_3PO_4?

Jul 10, 2018

It is $\text{149.087 g/mol}$.

#### Explanation:

Multiply the subscript for each element by its molar mass, which is its atomic weight in g/mol. In the case of ("NH"_4)_3", multiply the subscripts inside the parentheses by $3$.

Gram-formula mass of ("NH"_4)_3"PO"_4"

$\left(3 \times \text{14.007 g/mol N") + (12xx"1.008 g/mol H") + (1xx"30.974 g/mol P") + (4xx"15.999 g/mol O}\right) =$

$\text{149.087 g/mol}$ ("NH"_4)_3"PO"_4"