electrolysis
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why don’t covalent bonds conduct electricity
have no free electrons to carry a charge
covalent compounds act as
insulators
do ionic compounds conduct electricity
when molten or in solution because they have free ions able to carry a charge
during electrolysis, electrons move from ____ to ___
anode cathode
cations
positively charged ions
anions
negatively charged ions
where do cations in the electrolyte move to
migrate towards the negatively charged electrode
negatively charged electrode is the
cathode
positevely charged electrode is the
anode
anions in the electrolyte migrate towards
the positevely charged electrode
binary ionic compounds are
compounds consisting of just two elements joined together by ionic bonding
when binary ionic compounds get heated past their melting point, what happens
they become molten and can conduct electricity as their ions can move freely and carry a charge
cathode product will always be (for molten compounds)
a metal
anode product for molten compounds is
non metal
to make the aquoeus solution, what has been done
ionic compound dissolved in water
method for electrolysis of lead bromide
Add lead(II) bromide into a crucible and heat so it will turn molten, allowing ions to be free to move and conduct an electric charge Add two graphite rods as the electrodes and connect this to a power pack or battery Turn on the power pack or battery and allow electrolysis to take place
for lead bromide, what happens at the anode
negative bromide ions move towards positive electrode at the anode, they lose two electrons and form bromine atoms bubbling at anode is seen as bromine gas is given off
what happens at the cathode with lead bromide
positive lead ions move towards the negative electrode at the cathode they gain electrons to form a grey lead metal lead deposits on the bottom of the electrode
in the electrolysis of aqueous solutions, water molecules dissociate producing (2)
H+ OH-
for aqueous solutions, what happens at the anode
negatively charged OH- ions and non metal ions are attracted to the positive electrode
in electrolysis for aqueous solutions, what happens if halide ions are present
they are discharged at the anode, lose an electron and form a halogen
what is produced at the cathode in aqueous solution
• positevely charged H+ ions and metal ions are attracted to the cathode, but only one will gain electrons either hydrogen gas or metal will produce
at the cathode, in aqueous solutions, how do you know if a metal or hydrogen is produced
if metal is above hydrogen in the reactivity series, then hydrogen gas will be produced & bubbling is visible this is because more reactive ions remain in the solution, causing least reactive ion to be discharged
if you have a solution of any other common ions other than halides, at the anode, what is produced
oxygen