Test for halide ions

Question 1

Sodium/Potassium chloride + H₂SO₄(l)

Answer 1

NaCl(s) + H₂SO₄(l) → NaHSO₄(aq) + HCl(g)
HCl + excess H₂SO₄ → DOESNT HAPPEN BECAUSE CL- is a weak reducing agent

Question 2

Sodium/Potassium bromide + H₂SO₄(l)

Answer 2

NaBr(s) + H₂SO₄(l) → NaHSO₄(aq) + HBr(g)
HBr + H₂SO₄ → Br₂ + SO₂ + H₂O

Question 3

Sodium/Potassium iodide + H₂SO₄(l)

Answer 3

NaI(s) + H₂SO₄(l) → NaHSO₄(aq) + HI(g)
HI + H₂SO₄ → I₂ + SO₂ + H₂S + S + H₂O IODIDE ION IS STRONG REDUCING AGENT SO IT REDUCES SULFUR TO SO₂, S, H₂S
a) HI + H₂SO₄ → I₂ + SO₂ + H₂O
b) HI + H₂SO₄ → S + I₂ + H₂O
c) HI + H₂SO₄ → H₂S + I₂ + H₂O

Question 4

NaI(s) + H3PO₄(aq) →

Answer 4

HI(g) H3PO4 IS WEAK SO HI WILL FORM AND CAN BE EXTRACTED

Question 5

Positive result for Cl- ion

Answer 5

White fumes only

Question 6

Positive result for Br- ion

Answer 6

Brown gas

Question 7

Positive result for I- ion

Answer 7

Purple gas, Yellow solid (Sulfur), Rotten egg smell (H₂S)