Chem Question 1

1. When chlorine is added into halide, redox reaction occur
Cl2 + 2I- → 2Cl- + I2
Cl2 + 2Br- → 2Cl- + Br2
so the products of the reaction between potassium bromide and chlorine are potassium chloride and bromine, the products of the reaction between potassium iodide and chlorine are potassium chloride and iodine

2a. For the explanation of redox reaction, we MUST explain it in terms of oxidation number. In this case, the oxidation number of chlorine is decreased from 0 to -1, that means the chlorine is reduced; the oxidation number of iron(II) ion is increased to +3 from +2, that means the iron(II) ion is oxidized. So this is a redox reaction.

2b. Hydroxide ion is a reducing agent, and chlorine is an oxidizing agent.
4OH- + 2Cl2 → 4Cl- + O2 + 2H2O
Therefore, you can see the bubbles evolving to show the oxidation has taken place.

1a) Potassium bromide—names of products?
Potassium Chloride and Bromine 2KBr + Cl2 ---> 2KCl + Br2
Potassium iodide-- names of products?
Potassium Chloride and Iodine 2KI + Cl2 ---> 2KCl + I2
2a) 2Fe2+ + Cl2 ---> 2Fe3+ + 2Cl-
iron(II) is oxidized to iron(III)
Chlorine is reduced to Chloride.
This is a redox reaction.
2b)
Before the reaction, add NaOH to the solution. Green ppt of Fe(OH)2 would be formed.
After the reaction, add NaOH to the solution. Yellow ppt of Fe(OH)3 would be formed.