Writing Formulas
Write the formula for carbon dioxide.
CO₂
Is sodium chloride (NaCl) soluble or insoluble?
Soluble (all Group 1 compounds are soluble)
Sodium chloride + silver nitrate → silver chloride + sodium nitrate. Write the skeleton equation.
NaCl + AgNO₃ → AgCl + NaNO₃
NaCl + AgNO₃ → AgCl + NaNO₃
already balanced
Add state symbols: NaCl + AgNO₃ → AgCl + NaNO₃
NaCl(aq) + AgNO₃(aq) → AgCl(s) + NaNO₃(aq)
Write the formula for magnesium chloride.
MgCl₂
Is silver nitrate (AgNO₃) soluble or insoluble?
Soluble (all nitrates are soluble, no exceptions)
Potassium iodide + lead(II) nitrate → lead(II) iodide + potassium nitrate. Write the skeleton equation.
KI + Pb(NO₃)₂ → PbI₂ + KNO₃
KI + Pb(NO₃)₂ → PbI₂ + KNO₃
2KI + Pb(NO₃)₂ → PbI₂ + 2KNO₃
Potassium iodide reacts with lead(II) nitrate. Write the full balanced equation with states.
2KI(aq) + Pb(NO₃)₂(aq) → PbI₂(s) + 2KNO₃(aq)
Write the formula for calcium carbonate.
CaCO₃
Is barium hydroxide (Ba(OH)₂) soluble or insoluble?
Soluble (hydroxides are insoluble EXCEPT Group 1, Ba, Sr — Ca is slightly soluble)
Barium chloride + sodium sulfate → barium sulfate + sodium chloride. Write the skeleton equation.
BaCl₂ + Na₂SO₄ → BaSO₄ + NaCl
BaCl₂ + Na₂SO₄ → BaSO₄ + NaCl
BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
Barium chloride reacts with sodium sulfate. Write the full balanced equation with states.
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)
Write the formula for iron(III) sulfate.
Fe₂(SO₄)₃
Is lead(II) sulfate (PbSO₄) soluble or insoluble?
Insoluble (sulfates are soluble except Ba, Pb, Ca, Sr, Ag)
Iron(III) chloride + sodium hydroxide → iron(III) hydroxide + sodium chloride. Write the skeleton equation.
FeCl₃ + NaOH → Fe(OH)₃ + NaCl
FeCl₃ + NaOH → Fe(OH)₃ + NaCl
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
Sodium chloride solution is mixed with potassium nitrate solution. Write the full equation with states, or explain why none is needed.
No reaction — both possible products (NaNO₃ and KCl) are soluble, so no precipitate forms.
Write the formula for ammonium phosphate.
(NH₄)₃PO₄
Sodium carbonate solution is mixed with calcium chloride solution. Which product (if either) will precipitate?
Calcium carbonate (CaCO₃) — carbonates are insoluble except Group 1/NH₄⁺; sodium chloride formed stays dissolved.
Ammonium sulfate + barium nitrate → barium sulfate + ammonium nitrate. Write the skeleton equation.
(NH₄)₂SO₄ + Ba(NO₃)₂ → BaSO₄ + NH₄NO₃
Balance: Al₂(SO₄)₃ + BaCl₂ → BaSO₄ + AlCl₃
Al₂(SO₄)₃ + 3BaCl₂ → 3BaSO₄ + 2AlCl₃
Iron(III) chloride reacts with sodium hydroxide. Write the complete balanced equation with correct state symbols.
FeCl₃(aq) + 3NaOH(aq) → Fe(OH)₃(s) + 3NaCl(aq)