Electrolysis

What’s electrolysis?

process that splits ionic compounds into their different elements

How are electrolytes formed?

• when ionic compounds are melted or dissolved in water,

• the ions are free to move around and the solution will conduct electricity

What’s an electroli

• Ionic compounds that dissolve in water

• to make a solution that conducts electricity are called electrolytes

What happens at the electrodes?

• When a voltage (direct current) is applied across an electrolyte

• the charged ions are attracted to the electrode with the opposite charge to the ion

• Positively charged ions move to the negative electrode

• Negatively charged ions move to the positive electrode

What is the negative electrode?

Cathode

What’s the positive electrode?

Anode

What are ionic compounds?

• When simple ionic compounds are heated

• they will eventually melt

What are molten ionic compounds?

• The metal and non metal ions within the molten ionic compound become free to move

• so the liquid can undergo electrolysis

Where will the metal form?

At the negative electrode

Where will the non metal form?

At the positive electrode

How is electrolysis used to extract ores?

• used to extract reactive metals from molten ores

• these metals are more reactive than carbon

Why is the anode usually made of carbon?

It is a good conductor and is cheap

What’s the extraction of metals?

When a more reactive element will displace a less reactive element from its compound

What happens in the electrolysis of aluminium oxide?

• Aluminium oxide mixed with cryolite to lower melting point

• this reduces amount of energy needed and saves money

• cathode adn anode made of graphite

Why does the anode have to be replaced regularly?

Oxygen molecules produced at anode react with graphit forming CO₂

Why is electrolysis expensive?

• requires a lot of energy to melt compounds

• a lot of energy is needed to produce electric current

What happens in the elctrolysis of aqeous solutions?

• they are dissolved in water

• water molecules ionise forming H⁺ and OH^- ions

• electrodes are made out of platinum