C3.4 Flashcards
What is electrolysis
Electrolysis is the process by which an electric current is passed through a compound causing a chemical change.
What are the three things needed for electrolysis
An electrolyte - A compound in its liquid state or in solution which contains mobile ions and conducts electricity
Two electrodes - which conduct electricity to the electrolyte
Electrical supply such as a power pack or battery
What are the two electrodes
Cathode where positive ions go as it’s negatively charged
Anode where negative ions go to as it’s positively charged
What do you call it when ions become atoms or molecules at the electrodes
The ions have become discharged.
What happens when an ion becomes discharged
When an ion becomes discharged the ions in the electrolyte replace them by diffusion and convection.
What are inert electrodes
Inert electrodes are electrodes that aren’t changed during electrolysis usually made from un reactive materials such as copper or platinum.
What happens in electrolysis of solutions
Hydrogen is produced at the cathode unless an ion from a less reactive metal is present.
Oxygen is produced at the anode unless ions from an element in group 7 are present.
What does electroplating use
Electroplating uses non-inert electrodes.
What is the cathode and anode in electroplating
The cathode is the object that you want to coat
The anode is a piece of the metal you want to coat the object with.
What does the electrolyte contain
The electrolyte contains the ions of the metal you want to coat with.
What is the process of electroplating
During electroplating metal ions are discharged on the surface of the cathode. These ions are replaced by ions leaving the anode. Metal leaves the anode and is deposited on the cathode until it’s used up.
What is purification
Both electrodes made from the material you want to purify. Cathode purified anode is impure. Cathode gains the pure ions from anode and at the anode it decreases in mass and the impurities and collect under it.
