Chem 2 - Reaction rates, Salts and Electrolysis - Electrolysis

Revision cards for Electrolysis, hope this helps! :]

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Electrolysis

Electrolysis means Splitting up with Electricity:

- If you pass an electric current through an ionic substance thats molten or ina solution, it breaks down into the elements its made of

- It requires a liquid to conduct the electricity, called the electrolyte

- Electrolytes contain free ions, they're usually molten or dissolved ionic substances

- In either case its free ions which conduct electricity and allow the whole thing to work

- For an electrical circuit to be complete, there's got to be a flow of electrons. Electrons are taken away from ions at the positive electrode (Anode) and given to other ions at the negative electrode (Cathode). As ions gain or lose electrons they become atoms or molecules and are released

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Electrolysis 2

Electrolysis reactions involve Oxidation and Reduction

- Reduction is the gain of electrons

- Oxidation is the loss of electrons

Negative ions are attracted to the Positive electrode, and Positive ions are attracted to the Negative electrode.

An example of this is the electrolysis of Molten Sodium Chloride:

When you pass a current through Molten Sodium Chloride

- The Sodium Ions (Na+) are attracted to the negative electrode

- The Chlorine Ions (Cl-) are attracted to the positive electrode

- The Electrons that the Chlorine Ions have gained to become Ions, travel through the positive electrode, up to the power pack, back down the negative electrode and reaches the Sodium ions. This turns the Sodium and Chlorine Ions into Atoms.

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Electrolysis 3

A different scenario is the Electrolysis of a salt in a solution.

When a salt is dissolved in water, there will also be H+ and OH- Ions

For the example, we'll use Sodium Chloride again.

- Chlorine will be attracted to the positive electrode. The electrons it has gained to become an ion will run up the electrode and down to the negative electrode.

- The Sodium ions however, will this time will stay in the solution because they are more reactive than hydrogen

- The H+ Ions are attracted to the negative electrode. Here they combine with the electrons from the Chlorine Ions to form Hydrogen Molecules

- The OH- Ions bond with the Sodium Ions to form Sodium Hydroxide

So the end products are Hydrogen Gas, Sodium Hydroxide and Chlorine

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Comments

Lamise Hassan

Ah jus what i need - last min revision ;) thanks , also a useful acronym is OILRIG (oxidation is loss, reduction is gain) 

Cubix Rube

Ahh sorry man, meant to put that in :] Thanks! :]

bex

These notes are as backward as your name

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