The rest of the anions and a decision chart
Answers are for parents and teachers.
1
Balance and complete: (NH₄)₂SO₄ + BaCl₂ → ?
(NH₄)₂SO₄ + BaCl₂ → BaSO₄ + 2NH₄Cl; N 2, H 8, S 1, O 4, Ba 1, Cl 2 on both sides.
2
Write the equation of potassium chloride with silver nitrate, name the precipitate and say what happens to it in sunlight.
KCl + AgNO₃ → AgCl + KNO₃; AgCl is white and turns dark in sunlight.
3
Using 5NaNO₂ + 2KMnO₄ + 3H₂SO₄ → 5NaNO₃ + K₂SO₄ + 2MnSO₄ + 3H₂O, how many moles of KMnO₄ react with 0.25 mol of NaNO₂?
n(KMnO₄) = 0.25 × 2 ÷ 5 = 0.10 mol.
4
Sort into groups 1, 2 and 3: sulphite, chloride, phosphate, thiosulphate, iodide.
Group 1: sulphite, thiosulphate. Group 2: chloride, iodide. Group 3: phosphate.
5
Explain why a white precipitate with BaCl₂ alone is not enough to prove a sulphate.
Phosphate (and carbonate or sulphite) also give white barium salts; only the precipitate that stays in dilute HCl proves sulphate.