Hey there!
Magnesium molar mass: 24.305g
Phosphorus molar mass: 30.97g
Oxygen molar mass: 16g
Mg: 3 x 24.305 = 72.915
P: 2 x 30.97 = 61.94
O: 8 x 16 = 128
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262.855g
The molar mass of Mg₃(PO₄)₂ is 262.855 g/mol.
Hope this helps!
