electrolysis 5.5 Flashcards
what is electrolysis
breaking down of a compound using electricity
how does electrolysis occur
the substance to be broken down is connected into a circuit with a cell or battery
what is the positive electrode called
anode
what is the negative electrode called
cathode
characteristics of electrodes
solid that conducts electricity but is inert
what metals are usually used as electrodes
graphite (cheap)
platinum (expensive)
what is the electrolyte
the substance to be broken down
what are the only compounds that can be electrolytes
ionic compounds that are molten or dissolved as the ions are free to move
what are the positive ions called
cations as they are attracted to the cathode
what are the negative ions called
anions as the are attracted to the anode
what does the electrolysis of magnesium chloride form
magnesium and chlorine
what is seen at the anode in the electrolysis of magnesium chloride
bubbles of pale green gas
what attracts to the anode
non-metal ions that form molecules
what attracts to the cathode
metal ions form electrons
what is seen at the cathode in the electrolysis of magnesium chloride
grey solid would form on the surface
what does electrolysis of molten ionic compounds produce
its elements
what happens to water molecules during the electrolysis of aqueous compounds
water molecules disassociate to form H+ and OH- ions
how to pick which ion reacts at the anode
if a hailed ion (Cl-/Br-/I-) is present then the element is produced as normal
otherwise, O2 and H2O are produced
how to pick which ion reacts at the cathode
if the metal is less reactive than hydrogen then the element is produced as normal
otherwise, H2 is produced
what happens to the ions that don’t react
they remain leftover in the solution as a third product
