Electrochemistry

What is electrolysis

The use of electricity to bring about a chemical reaction in an electrolyte

Electrolyte

A compound which when molten or dissolved in water will conduct an electric current

Battery

Provides energy for the reaction to occur

What do electrodes do

Dip into the electrolyte and make chemical contact

What are inert electrodes

They do not react with the electrolyte

What are active electrodes

They react with the electrolyte

What charge is an anode

Positive

What charge is a cathode

Negative

What elements make up inert electrodes

Graphite (carbon) and platinum

What elements are in active electrodes

Copper and iron

Outline the main events during electrolysis

1. Anode attracts to anions from the electrolyte

2. Energy from the battery allows the anions to lose electrons to the anode (oxidation of anions)

3. Cathode attracts the cations from the electrolyte

4. Energy from the battery allows the cations to gain electrons from the cathode (reduction of cations)

Using electrolysis on a solution of potassium iodide, with added phenolphthalein using inert electrodes

Observation: Brown colour around anode, pink colour around cathode

Using electrolysis on acidified water using inert electrodes

Small amount of H2SO4 is added to allow the water to conduct electricity.

Observation: one volume of oxygen gas is produced at anode, two volumes of hydrogen gas are produced at cathode

Using electrolysis on a solution of sodium sulphate with universal indicator using inert electrodes

Observation: Solution turns red in anode, solution turns blue in cathode

Using electrolysis on a solution of copper (II) sulphate using copper electrodes

Observation: Cathode becomes smaller, anode grows

This process is used to purify copper in industry for electrics

Showing the movement of electrons due to an electronic field

Copper chromate is green in solution, as it is made up of blue Cu2+ and yellow CrO4 2-.

If put into an electronic field, the Cu2+ is attracted to the cathode and the CrO4 2- is attracted to the anode. The movement of electrons results in visible colour separation.

What is electroplating

Where electrolysis is used to put a layer of one metal onto the surface of another

Uses of electrolysis

Used to make coins or cutlery more attractive

Used to prevent rust by plating reactive and less reactive metals

Conditions needed for electrolysis

1. The metal to be plated must be the cathode

2. The metal to be plated with must be the anode

3. The electrolyte must contain ions of the metal we are plating with

What is the electrochemical series?

Series of metals arranged in order of their ability to be oxidised

What is the acronym for the electrochemical series

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Please Send Lions, Cats, Monkeys And Zebras Into Lovely Hot Countries, Signed General Penguin

Potassium, Sodium, Lithium, Calcium, Magnesium, Alluminum, Zinc, Iron, Lead, Hydrogen, Carbon, Silver, Gold, Platinum