Question

What mass of solute should you measure out in order to make 1,000 mL of a 0.3 M solution of magnesium phosphate Mg3(PO4)2?

Answer 1

Hey there !

Molecular Weight: 262.86 g/mol

Volume in liters : 1,000 mL => 1,000 / 1000 => 1 L

Number of moles of solution :

number of moles = volume x molarity

number of moles = 1 x 0.3  => 0.3 moles

Therefore:

1 mole Mg₃(PO₄)₂ ------------------- 262.86 g

0.3 moles ----------------------------- mass of Mg₃(PO₄)₂  ??

mass of Mg₃(PO₄)₂ = 0.3 x 262.86 / 1

mass of Mg(PO₄)₂ => 78.858 g

Hope this helps!