A-level chemistry

1. Reactions of the Halogens (3) Aim To identify and write full redox equations for the Reactions of Halogens with halide ions.

2. Redox with halogens and halides Reaction between Chlorine (aq) and Potassium Bromide (aq) Equation for the reaction: Cl 2(aq) + 2KBr (aq) 2KCl (aq) + Br 2(aq) Ionic half equation for Cl 2 Ionic half equation for Br -1 Overall ionic equation: What substance is the oxidising agent?

3. 2) Solubility in Water and Cyclohexane Take a few cm 3 of each halogen solution in water in a test tube. Use a bung to stopper the test tube and shake the solution with an equal volume of cyclohexane. Fill in the table below (CARE: chlorine and bromine solutions have harmful vapours. Avoid breathing the fumes from the solutions). Questions Are halogens more soluble in water or in organic solvents (e.g. cyclohexane)? Why do you think this is? Cl 2 Br 2 I 2 Colour of halogen solution in water Colour of halogen solution in cyclohexane

4. Experiment See instruction sheet.

5. Reactions of the Halogens with Halide solutions. Add about 2ml of halide solution to a test tube. Add about the same volume of halogen solution to it. Observe carefully any colour change. Add a small volume of cyclohexane to the test tube and shake carefully. What product has been made in the reaction?

6. Results Table. Iodine Bromine Chlorine Iodide Bromide Chloride Halogen and halide solutions

7. Equation work Write equations for the reactions that took place using the same format as for the reaction of Chlorine and potassium bromide starting with the half ionic equations.

8. Redox with halogens and halides Reaction between Chlorine (aq) and Potassium Iodide (aq) Equation for the reaction: Cl 2(aq) + 2KI (aq) 2KCl (aq) + I 2(aq) Ionic half equation for Cl 2 Ionic half equation for I -1 Overall ionic equation: What substance is the oxidising agent?

9. Redox with halogens and halides Reaction between Bromine (aq) and Potassium Iodide (aq) Equation for the reaction: Br 2(aq) + 2KI (aq) 2KBr (aq) + I 2(aq) Ionic half equation for Br 2 Ionic half equation for I -1 Overall ionic equation: What substance is the oxidising agent?

10. Relative strength as oxidising agents Why does the oxidising power of halogens decrease as the group is descended? What is the strongest oxidising agent in the grp? Why?

11. Homework Research the displacement reaction used to extract bromine from sea water. Revise for the resit test on Monday after half term. Write up experiments – experiment book handed in on Monday after half term. There will be a test on the 2 nd Monday after half term on all the work you have done so far -