Electrolysis: Potassium Iodide (Molten)

Aim:

To find the oxidising and reducing agents of molten potassium iodide

Equipment:

1x U-tube made out of copper
A power supply
2x wires connecting power pack to carbon electrodes
2x carbon inert electrodes
Molten potassium iodide

Safety:

·         Wear protective gear such as thick boots, high durable safety glasses, lab coat and extremely durable gloves

·         Avoid contact with any molten potassium iodide because 680^oC > is a hot temperature

Procedure:

1.       Collect all equipment needed and make sure all safety precautions are done or set.

2.       Setup the apparatus the same way as the previous experiment (Electrolysis: Potassium Iodide (solution))

3.       Add molten potassium iodide to the copper U-tube and turn the power supply on.

4.       Observe and record all results.

Predicted Results:

Anode	Cathode
Collecting the gas and cooling it down allows us to see a purple/black coloured substance at room temperature	Silvery solid starts forming over the carbon electrode until there is no molten potassium iodide is left

Redox:

2I⁻ _(l) → I₂ _(g) + 2e⁻   Oxidising

2K⁺ _(l) + 2e⁻   → 2K_(s) Reducing

2I⁻ _(l) +2K⁺ _(l) → I₂ _(g) +2K_(s) Redox Equation

Discussion:

From the procedures of this experiment we can see right at the start that it is very dangerous because of many parameters. First of all, the temperature of the molten potassium iodide is extremely high. This is because of its ionic bond creating a very strong bond within the ions, and breaking these bonds requires high amount of energy such as heat. Therefore, because of these dangerous temperatures, safety equipment is compulsory.

Our group could not experiment this theory as the extreme temperatures, lack of equipment and lack of space all stopped us because of the high risks.

To conclude, we can say that this experiment is not practically possible to do in a school environment; however, this experiment is done on a massive scale in the mining industry allowing the separation of a compound to its elemental form such as potassium iodide.

Electrolysis: Potassium Iodide (Solution)

Aim:

To find the oxidising and reducing agent in an aqueous solution of potassium iodide

Equipment:

1x U-tube
Phenolphthalein indicator
0.5 mol L⁻ Potassium Iodide Solution
About 15ml of distilled water
A power supply
2x carbon inhert electrodes
2x wires connecting power pack to carbon electrodes

Procedure:

1.       Collect all equipment needed and make create an observation and reaction table

2.       The diagram below shows the basis of the apparatus’ setup.

3.       Once the setup looks like the diagram below add a mix of 15 ml of potassium iodide and 15 ml of the distilled water

4.       Turn the power (6V supply should be enough)

5.       Once you see some reaction take place, add a few drops of the phenolphthalein indicator to check for any type of bases that may be in the solution

6.      

Record all results and observations.

Results:

Anode	Cathode
Solution around anode becomes yellowish/brown in colour.	Solution around cathode bubbles and is clear until Phenolphthalein indicator is added then solution becomes purple.

Redox:

2I⁻ _(aq) → I₂ _(aq) + 2e⁻   Oxidised
2H₂O _(l) + 2e⁻   → H₂ _(g) + 2OH⁻ _(aq) Reduced
2I⁻ _(aq) + 2H₂O (l) → I₂ _(aq) + H₂ _(g) + 2OH⁻ _(aq) Redox Equation

Discussion:

This experiment has shown and taught us a few lessons. First off we can see that water is a stronger oxidising agent than potassium. For this reason water reacts at the cathode instead of potassium, therefore forming hydrogen gas and hydroxide ions. To prove this we added a few drops of phenolphthalein indicator which resulted the solution to turn to purple colour at the cathode, in other words meaning hydroxide ions as the phenolphthalein turns purple when it comes in contact with a basic solution and colourless with an acidic solution.

The anode has a very different story as the water is not a stronger reductant than iodine, therefore, we can say that iodine reacts at the ₂ is formed at the anode however our group could not confirm this to be Iodine gas as the solution turned brownish/yellow, and the WACE WA data sheet stated that I₂ in an aqueous solution turns to a brownish/yellow colour. Therefore, this would mean that the I₂ is actually an ion.

anode instead of the water. We can see that I

Our experiment resulted in near perfect results it was conducted more than once and all steps being performed as perfectly possible.

To conclude, we can see that water is a stronger oxidising agent compared to potassium, however it is a weaker reducing agent compared to iodine