Answer:
24.5 g of NaCl
Explanation:
We begin from the balanced reaction:
3MgCl₂ + 2Na₃PO₄ → 6NaCl + Mg₃(PO₄)₂
If the sodium phosphate is in excess, then the limting reagent is the magnessium chloride.
We convert mass to moles:
20 g . 1mol / 95.2g = 0.210 moles.
3 moles of MgCl₂ can produce 6 moles of NaCl
0.210 moles of salt, may produce (0.210 . 6) /3 = 0.420 moles
Ratio of reactant is twice the product
We convert the moles to mass:
0.420 mol . 58.45 g/mol = 24.5 g
