Electrolysis End of unit

At which electrode does oxidation happen during electrolysis?

The anode

What is oxidation?

The loss of an electron

What is reduction?

Gain of electrons

Every metal besides .. and ., react with oxygen

Silver and gold

How do you isolate elements below carbon in the reactivity series?

React them with carbon

What are the rules of collection at the cathode?

If the metal is higher than hydrogen in the reactivity series, then hydrogen is made

If the metal is lower than hydrogen in the reactivity series, it costs the electrode.

What are the rules of collection at the anode?

If halide ions are present, halogen gas is produced.

If halide ions aren’t present, oxygen is produced.

What is an ore?

Contains a metal compound

What is graphite made of?

Carbon and oxygen

Why are graphite anodes replaced every month?

Carbon and Oxygen will slowly make Co2 as oxygen ions slowly hit the carbon. They break down and decompose.

What is bouxile?

Aluminium oxide

How is the charge carried in a solid circuit?

Delocalised electrons

How is the charge carried in an electrolyte/solution? (the liquid at the bottom)

Ions

How do halogens move around?

In pairs

How is a gas collected at the anode?

Bubbles

How do electrons move in electrolysis?

Carry the charge from one side to another

What is another name from Sodium chloride solution?

Brine

Why must things be molten or dissolved?

If not, ions cannot travel or move around to carry the charge between cathodes

In a pure metal..

layers can slide over each other

What does it mean if a solution is acidic?

There’s a high concentration of hydrogen ions

What happens if a solution is alkali?

There’s a low concentration of hydrogen ions

When the pH unit decreases by 1..

the hydrogen ion concentration in a solution increases by 10

The more acidic the solution..

the higher the concentration of hydrogen

Example of weak and strong acid

Weak = Vinegar

Strong = Hydrochloric

What does cryolite do?

Reduces melting point of aluminium oxide so less energy is required

Oxygen is produced at the positive electrode unless the solution contains..

Halide ions

To conduct electricity in a solid,,

It must have delocalised electrons in the structure to carry the charge

To conduct electricity in a liquid..

Ions must be available to move and carry the charge through the fluid

What is a limiting reactant?

The one that runs our first

Why do we add excess?

To ensure it’s all reacted

Why are metal atoms always oxidised?

Metal atoms always lose electrons

What is a redox reaction?

Oxidation and reduction happen at the same time

What happens in electrolysis?

Compound decomposes or breaks down

What happens at the cathode?

Positive ions gain electrons at the negative cathode

What happens at the anode?

Negative ions lose electrons at the negative anode

What happens in a molten compound?

Positive ions go to the cathode, negative ions go to the anode

What happens in aqueous solutions?

Water contains hydrogen and hydroxide molecules, Positive ion goes to cathode unless more reactive than hydrogen, oxygen atom goes to anode unless halide ion is present