Electrolysis

• Electrolysis is the process of using electricity to split up a compound into its elements
• To separate elements in insoluble ionic compounds like lead bromide using electrolysis:

  • An electrolyte (liquid or solution containing an ionic compound) is needed, where ions are free to move
  • For insoluble compounds like lead bromide, it needs to be melted to get a molten liquid for ions to move freely
  • Electrodes are required: the positive electrode (anode) attracts negative ions, and the negative electrode (cathode) attracts positive ions
  • A power supply like a battery is used to drive the flow of electrons through the electrolyte
• During electrolysis of molten lead bromide:

  • Negative bromide ions are attracted to the positive anode, where they are discharged to form bromine gas
  • Positive lead ions are attracted to the negative cathode, where they are discharged to form pure lead
• Electrolysis is used to extract reactive metals from their oxides by first melting them into their molten ionic compounds
• Metals often exist as oxides like aluminium oxide or copper oxide
• To remove oxygen and isolate the pure metal, reduction with carbon can be used for metals less reactive than carbon like zinc, iron, and copper
• For more reactive metals, electrolysis is required, which is more expensive and energy-intensive
• Electrolysis is a process that separates ionic compounds into their pure elements by passing an electric current through an electrolyte
• In the case of aluminium oxide, electrolysis can split it into pure aluminium and oxygen
• Aluminium oxide is solid, so before electrolysis, it needs to be turned into molten form by mixing it with cryolite to lower the melting point
• Remember the mnemonic "oil rig" where oxidation is the loss of electrons and reduction is the gain of electrons
• Electrolysis is a technique used to split compounds into their elements by passing an electric current through an electrolyte
• For insoluble compounds like most metal oxides, they need to be melted to become a molten liquid for the electrolysis process
• Soluble compounds like copper sulfate and sodium chloride can be dissolved in water to create the electrolyte for the electrolysis process
• In an electrolysis experiment, you need a beaker full of electrolyte, two electrodes (positive anode on the right and negative cathode on the left), a wire joining the electrodes, and a power supply
• The cathode attracts positive ions, such as the metal ion from the compound and the hydrogen ion from water, but only discharges one of these ions based on reactivity
• The rule for the cathode is that the ion of the least reactive element will be the one discharged
• At the anode, if a halide ion is present, it will be discharged; if not, the hydroxide ion will be discharged
• In an aqueous solution of copper sulfate, the cathode will discharge copper ions, forming pure copper, while the anode will discharge hydroxide ions, forming oxygen and water
• In an aqueous solution of sodium chloride, the cathode will discharge hydrogen ions to form hydrogen gas, and the anode will discharge chloride ions to form chlorine gas