Chem F Flashcards
What is electrolysis?
the breaking down of a ionic compound using electricity
what is a ion?
a charged particle from an atom gaining or losing electrons
In electrolysis, what do metals form?
positive ions
In electrolysis, what do non-metals form?
negative ions
what are the conditions needed for electrolysis?
An ionic compound that is either molten or in a solution (AQ) so that the ions are free to move and carry charge. The solution is known as electrolyte.
what is the anode?
positive electrode
what is the cathode?
negative electrode
what happens at each electrode?
At the -ve electrode (cathode): +ve ions are attracted to the negative electrode and gain electrons to produce elements.
at the +ve electrode (anode): -ve ions are attracted to the positive electrode and lose electrons to produce elements
what is produced at the + ve electrode?
oxygen and water are produced
What is produced at the -ve electrode?
if the metal is more reactive than hydrogen then hydrogen is produced, if it is less reactive then the metal is produced.
what is the required practical of electrolysis? (NaCl)
when NaCl is dissolved in water we obtain Na+ (aq) and Cl-(aq). We would expect to therefore obtain pure Na at the cathode. However, sodium is more reactive than hydrogen, so we expect hydrogen to be produced at the cathode BUT the non-metal is a halogen (chlorine) so oxygen is produced.
How can metals be extracted using electrolysis?
metals more reactive than carbon can be extracted from their ores by electrolysis of the molten metal.
How can aluminium be extracted?
aluminium can be extracted from aluminium oxide. Aluminium oxide is dissolved in molten cryolite. Cryolite reduces the energy costs for the reaction because it has a lower melting point than aluminium oxide.
