| What does Oxidation mean? | -Reaction with Oxygen
-Adding Oxygen to a Substance
-Removing Electrons |
| What does Reduction mean? | -Removing Oxygen
-Adding Electrons |
| Take Fe²O³ + 3CO ---> 2Fe + 3CO²
Which is here Reduced, and Oxidised [Terms of Oxygen] | -Iron Oxide becomes Iron. Iron Oxide is Reduced
-Carbon Monoxide becomes Caron Dioxide. Carbon is Oxidised |
| What does a Redox Reaction mean? | -Simply means Oxidation and Reduction takes place in the Same Reaction |
| What is an Oxidising Agent? | -This is something that takes Electrons, therefore being Reduced
-This is something that Loses Oxygen, therefore being Reduced |
| What is an Reducing Agent? | -This is something that Loses/Gains Electrons, therefore being Oxidised
-This is something that Gets Oxygens, therefore being Oxidised |
| What do Half Equations show? | -Simply show how Electrons move in a Reaction |
| Using Fe + 2H+ ---> Fe²+ + H²
-Which one is the Oxidising Agent [Being Reduced]
-Which one is the Reducing Agent [Being Oxidised] | -Iron here is being the Reducing Agent. This is because it Loses electrons to the Hydrogen Ions. [Fe = Fe²+ + 2e-]
-Hydrogen here is being the Oxidised Agent. This is because it Gains Electrons from the Iron atom [2H+ + 2e- --> H²] |
| Using Cu²+ + Mg ----> Cu + Mg²+
-Which element has been Reduced? | 1. Find out if each Element has Gained, or Lost Electrons by using Half Equations. [Cu²+ + 2e- ---> Cu] [Mg ---> Mg²+ + 2e-]
2. Reduction is Gaining Electrons, and in this case, its Copper. |
| What is Electrolysis? What happens? | -This is simply Breaking down a Substance using Electricity
-An Electric Current goes Through an Electrolyte, making it Decompose.
-The Positive Ions, called Cations, go towards the Cathode, which is a Negative Electrode, making the Cations Reduced [Gain Electrons]
-The Negative Ions, called Anions, go towards the Anode, which is a Positive Electrode, making the Anions Oxidised [Loses Electrons]
-As the Ions become Uncharged, they becomes Discharged from the Solution |
| What is an Electrolyte? | -Simply a Molten/Dissolved Ionic Compound |
| What is an electrochemical Cell? | -This is a Circuit, that is made up of the
-Anode
-Cathode
-Electrolyte
-Power Source [Cell, Battery]
-Wires connecting the 2 electrodes |
| Why can't Ionic Solids be Electrolysed? Why can Molten Ionic Compounds? | -This comes back to the fact that the Ions are in Fixed Positions, and so Cant Move. No Movement = No Electricity
-Molten Ionic Compounds can, because the Ions can move Around. Movement of Charged Particles = Current = Electricity |
| What happens at the Cathode, and Anode? | -The Positive Metal Ions gain Electrons [Reduced] to become Atoms at the Cathode [Cathode is Negative]
-The Negative Ions lose Electrons [Oxidised] to become Atoms at the Anode [Anode is Positive] |
| Given an Example of what would happen with Lead Bromide in terms of Electrolysis. | -You would see Beads of Molten Leads being formed at the Cathode
[Pb²+ + 2e- ---> Pb] Lead is being Reduced
-You would see Brown Vapour, signifying Bromide Gas at the Anode.
[2Br- ---> Br² + 2e-] Bromine is being Oxidised |
| What would be at the Cathode and Anode for:
-Lead Iodide [PbI²]
-Potassium Chloride [KCl]
-Aluminium Oxide [Al²O³]
Also give the Half Equations for each Element | Lead Iodide:
-Lead would be at Cathode [Pb²+ + 2e- --->Pb]
-Iodine would be at Anode [2I- ---> I² + 2e-]
Potassium Chloride
-Potassium would be at Cathode [K+ + e- -->K]
-Chloride would be at Anode [2Cl- ---> Cl² + 2e-] [Chlorine Gas]
Aluminium Oxide:
-Aluminium would be Cathode [Al³+ + 3e- ---> Al]
-Oxygen would be at Anode [2O²- ---> O² + 4e-] |
| Is there any pattern with Electrolysis with Molten/Dissovled Ionic Compounds? | -Yes
-Metals /G1-2 go to the Cathode
-Non-Metals go to the Anode |
| What can happen else in Electrolysis in Aqueous Solutions? | -The Hydrogen Ions [H+] and the Hydroxide Ions [OH-] will also Form.
-This change is Reversible |
| So what will happen if Electrolysis happens in an Aqueous Solution? | -Not only will the Compound split in its Ions, but the Water will
-The cathode will have the Metal Ions, and the Hydrogen Ions.
-Hydrogen Gas will be made if the Metal is more Reactive than Hydrogen [Sodium]
-A Solid layer of Pure Metal will be made, if Less Reactive than Hydrogen [Copper or Silver]
-The Anode will have Molecules of Halide Ions [G7] if they are Present
-If there is no Halide Ions, Oxygen will be made from the Hydroxide Ions |
| -What happens when Sodium Chloride is Dissolved in Water, and is being used for Electrolysis? How can you be sure of this? | -4 Ions will appear. Na+, Cl-, OH- and H+
-Sodium is more Reactive than Hydrogen, so the Cathode will see Hydrogen Gas be made [2H+ + 2e- ---> H²]
-This can be proven, by using the Squeaky Pop Test
-Chlorine is a Halide Ion, so the Anode will see Chlorine Gas be made [2Cl- ---> Cl² + 2e-]
-This can be Proven by using litmus Paper. Litmus Paper will become White if Chlorine is Present. [If Red for a moment, its because Chlorine is Acidic] |
| How can you set up an Electrochemical Cell? [Copper Sulphate] | -Get 2 Inert Electrodes [Platinum or Carbon] and clean using Sandpaper
-Make sure you don't touch it, as you can give Grease to it
-Place both of the Electrodes into a Beaker that has your Electrolyte
-Connect the Electrodes to a Cell/Battery via Wires |
| What happens to an Aqueous Solution of Copper Sulphate when Electrolysis takes place? | -4 Ions appear. Cu²+, SO⁴²-, H+ and OH-
-Copper is less Reactive than Hydrogen, so the Cathode sees Copper Metal being Formed. This coats the Cathode
[Cu²+ + 2e- ---> Cu]
-No Halide Ions are here, so Oxygen and Water is made.
[4OH- --> O² + 2H²O + 4 e-]
-This can be proven as Oxygen can Relight a Glowing Splint |
| What are Special about Non-Inert Electrodes | -They can Decompose into the Electrolyte
-Copper Electrodes are an Example |
| What happens if you use Copper Electrodes in an Electrolysis Reaction, using an Aqueous Solution of Copper Sulphate? What happens to the Masses? | -Everything will seem the same, until you notice the Mass of the Anode Decreasing, and the Mass of the Cathode Increasing.
-This is because Copper from the Anode, is Transferred to the Cathode
-This can happen because the Electrical Supply makes the Electrons rip Away from the Copper atoms, in the Anode making them enter the Solution as Cu²+
-And then it gets Attracted to the Negative Electrode, which is the Cathode and it makes them back to Copper Atoms.
-And Since Copper is less Reactive than Hydrogen, it will Stay There. |
