GCSE Chemistry (AQA)

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Process of Electrolysis

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Chemical changes Electrolysis

Process of Electrolysis

7:08 Electrolysis of Ionic Compounds and Metal Extraction
Spec 4.4.3.1
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  • Ionic compounds, when melted or dissolved in water, have free-moving ions.
  • Ionic compounds consist of positively and negatively charged ions.
  • Example: Molten zinc chloride (ZnCl2) has zinc ions (Zn2+) and chloride ions (Cl-).
  • In liquid form, ions are not joined and move independently.
  • In solutions, such as table salt (NaCl) dissolved in water, ions also separate and move freely.
  • These liquids and solutions can conduct electricity and are called electrolytes.
  • Pure water does not conduct electricity; it needs dissolved ions to become an electrolyte.
  • Electrolysis is a process that uses electricity to split up an electrolyte.
  • Electrodes (metal rods) are dipped into the electrolyte to form a complete circuit.
  • Electrodes are usually made of graphite or metal and are inert (non-reactive).
  • The positive electrode is called the anode, and the negative electrode is called the cathode.
  • The acronym PANIC helps remember: Positive Anode, Negative Is Cathode.
  • When the power supply is turned on, positive ions move to the cathode, and negative ions move to the anode.
  • At the anode, negative ions lose electrons to become neutral, forming elements like chlorine gas.
  • At the cathode, positive ions gain electrons to become neutral, forming elements like solid zinc.
  • The electrolysis process separates elements from ionic compounds.

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