1. Write the unbalanced equation:
Hg(NO₃)₂ (aq) + Na₃PO₄ (aq) → Hg₃(PO₄)₂ (s) + NaNO₃ (aq)
2. Identify the reactants and products:
* Reactants: Mercury(II) nitrate (Hg(NO₃)₂) and sodium phosphate (Na₃PO₄)
* Products: Mercury(II) phosphate (Hg₃(PO₄)₂) and sodium nitrate (NaNO₃)
3. Balance the atoms:
* Mercury (Hg): There are 3 Hg atoms on the product side and only 1 on the reactant side. Put a coefficient of 3 in front of Hg(NO₃)₂.
* Phosphate (PO₄): There are 2 PO₄ groups on the product side and only 1 on the reactant side. Put a coefficient of 2 in front of Na₃PO₄.
* Sodium (Na): There are 6 Na atoms on the reactant side (2 x 3) and only 1 on the product side. Put a coefficient of 6 in front of NaNO₃.
* Nitrate (NO₃): There are 6 NO₃ groups on the reactant side (3 x 2) and now also 6 on the product side (6 x 1).
4. The balanced equation:
3Hg(NO₃)₂ (aq) + 2Na₃PO₄ (aq) → Hg₃(PO₄)₂ (s) + 6NaNO₃ (aq)
Important Note: This reaction produces a precipitate, mercury(II) phosphate (Hg₃(PO₄)₂). The (s) in the equation indicates that it is a solid.
