The following equation is not balanced:

Na

3

PO

4

+MgCl

2

→Mg

3

(PO

4

)

2

+NaCl

Part A

Notice that “PO

4

” appears in two different places in this chemical equation. PO

 3−

4

 is a polyatomic ion called phosphate . What number should be placed in front of Na

3

PO

4

 to give the same total number of phosphate ions on each side of the equation?

?Na

3

PO

4

+MgCl

2

→Mg

3

(PO

4

)

2

+NaCl

Express your answer numerically as an integer.