Halogenes

Question 1

Reaction of chlorine with metals:

Answer 1

Fe(s) + 3 Cl2(g) → 2 FeCl3(s)

Question 2

Production of bromine from seawater:

Answer 2

2 Br–(aq) + Cl2(g) → Br2(l) + 2 Cl–(aq)
2 NaBr + Cl2 → Br2 + 2 NaCl

Question 3

Production of iodine from the brine from oil wells:

Answer 3

Cl2(g) + 2 I–(aq) → I2(aq) + 2 Cl–( aq)
Cl2(g) + 2 NaI → I2 + 2 NaCl

Question 4

Production of interhalogenides:

Answer 4

Cl2(g) + 3 F2(g) → 2 ClF3(g)
Cl2(g) + 5 F2(g) → 2 ClF5(g)

Question 5

Production of hydrogen halogenides:

Answer 5

H2(g) + X2(g) → 2 HX(g)
CaF2(s) + 2 H2SO4(aq, conc.) → Ca(HSO4)2(aq) + 2 HF(g)

Question 6

Production of HBr and HI using phosphorous acid:

Answer 6

KI(s) + H3PO4(aq) →KH2PO4(aq) + HI(g)

Question 7

Disproportionation of chlorine in the water:

Answer 7

Cl2 (g) + H2O(aq) → HClO (aq) + HCl (aq)

Question 8

Disproportionation of chlorine in the alkali:

Answer 8

Cl2 (g) + 2 OH-(aq) → ClO-(aq) + Cl−1-(aq) + H2O(l)
Cl2 + 2 NaOH → NaClO + NaCl + H2O

Question 9

Decomposition of hypochloric acid:

Answer 9

2HClO(aq) → 2H+(aq) + 2 Cl–(aq) + O2(g)
2HClO → 2 HCl + O2

Question 10

Production of chlorate ions:

Answer 10

3 Cl2(g) + 6 OH–(aq) →ClO3–(aq) + 5 Cl–(aq) + 3 H2O(l)
3 Cl2 + 6 NaOH → NaClO3 + 5 NaCl + 3 H2O

Question 11

Decomposition of chlorates:

Answer 11

4 KClO3(s) →3 KClO4(s) + KCl(s)
2 KClO3(s) → 2 KCl(s) + 3 O2(g)

Question 12

Production of chlorine dioxide:

Answer 12

2 NaClO3(aq) + SO2(g) + H2SO4(aq, dilute) →
2NaHSO4(aq) + 2 ClO2(g)

Question 13

Reaction of ammonium perchlorate with aluminum:

Answer 13

3NH4ClO4(s) + 3 Al(s) → Al2O3(s) + AlCl3(s) + 6 H2O(g) + 3 NO(g)