electrolysis

Examples of electrolysis in the following topics:

• Electrolysis of Sodium Chloride

  • Two commonly used methods of electrolysis involve molten sodium chloride and aqueous sodium chloride.
  • Electrolysis of a molten salt produces the elements from the salt.
  • So, the electrolysis of WCl4 produces W and Cl2.
  • Electrolysis of aqueous NaCl results in hydrogen and chloride gas.
  • Predict the products of electrolysis of sodium chloride under molten and aqueous conditions

• Electrolysis of Water

  • Pure water cannot undergo significant electrolysis without an electrolyte, such as an acid or a base.
  • Pure water cannot undergo significant electrolysis without adding an electrolyte.
  • For example, electrolysis of a solution of sulfuric acid or of a salt, such as NaNO3, results in the decomposition of water at both electrodes:
  • Device invented by Johann Wilhelm Ritter to develop the electrolysis of water.
  • Recall the properties of an electrolyte that enable the electrolysis of water

• Electrolytic Cells

  • Electrolysis uses electrical energy to induce a chemical reaction, which then takes place in an electrolytic cell.
  • In chemistry and manufacturing, electrolysis is a method of using a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction.
  • Electrolysis is commercially important as a stage in the process of separating elements from naturally occurring sources such as ore.
  • Electrolysis can sometimes be thought of as running a non-spontaneous galvanic cell.
  • If the ions are not mobile, as in a solid salt, then electrolysis cannot occur.

• Predicting the Products of Electrolysis

  • In order to predict the products of electrolysis, we first need to understand what electrolysis is and how it works.
  • Electrolysis is a method of separating bonded elements and compounds by passing an electric current through them.
  • If the ions are not mobile, as in a solid salt, then electrolysis cannot occur.
  • Electrolysis reactions involving H+ ions are fairly common in acidic solutions.
  • It is possible to have electrolysis involving gases.

• Electrolysis Stoichiometry

  • The amount of chemical change that occurs in electrolysis is stoichiometrically related to the amount of electrons that pass through the cell.
  • This relation was first formulated by Michael Faraday in 1832, in the form of two laws of electrolysis:
  • The weights of substances formed at an electrode during electrolysis are directly proportional to the quantity of electricity that passes through the electrolyte.
  • Most stoichiometric problems involving electrolysis can be solved without explicit use of Faraday's laws.

• The Hydrogen Economy

  • Currently, global hydrogen production is 48% from natural gas, 30% from oil, 18% from coal and 4% from water electrolysis.
  • Fuel cells require less energy input than other alternatives and perform water electrolysis at lower temperatures, both of which have the potential of reducing the overall cost of hydrogen production.
  • Other methods include photoelectrocatalytic production, thermochemical production, and high temperature and pressure electrolysis.
  • Other issues include the fact that hydrogen generation via electrolysis requires a greater energy input than directly using renewable energy, and the possibility of other side products.

• Extractive Metallurgy

  • Electrowinning is an electrolysis process used to recover metals in aqueous solution, usually as the result of an ore having undergone one or more hydrometallurgical processes.
  • Fused salt electrolysis is another electrometallurgical process whereby the valuable metal is dissolved into a molten salt, which acts as the electrolyte, and the valuable metal collects on the cathode of the cell.
  • The scope of electrometallurgy has significant overlap with the areas of hydrometallurgy and (in the case of fused salt electrolysis) pyrometallurgy.

• Electrolytic Properties

  • Electrolysis reactions involving H+ ions are fairly common in acidic solutions, while reactions involving OH- (hydroxide ions) are common in alkaline water solutions.
  • It is possible to have electrolysis involving gases.

• Metallurgy

  • Electrowinning is an electrolysis process used to recover metals in aqueous solution, usually as the result of an ore having undergone one or more hydrometallurgical processes.
  • The scope of electrometallurgy has significant overlap with the areas of hydrometallurgy and (in the case of fused salt electrolysis) pyrometallurgy.

• Aluminum

  • The simplest and safest way is to connect a battery to the sample and perform electrolysis under either an inert atmosphere (like argon gas) or vacuum conditions.