electrolysis Flashcards
electrodes made of
electrolysis
graphite/Pt (non-react)
others (reactive)
simple cell
made of 2 diff materials
electrolyte must be…
- must be conductor of electricity
- must be ionic compound (aq/molten) (aq for simple cell)
electrolyte undergoes chemical reaction
components of electrolysis
- batteries
- wires
- electrodes
- electrolyte
components of simple cell
voltmeter/ammeter/lightbulb/resistor
- wires
- electrodes
- electrolyte
why cannot do electrolysis on solid ionic compound
cannot conduct electricity, solid form
When NaCl (l) means…
- molten
- pure
binary
When NaCl (aq) means…
- aqueous
- impure
neg/pos charge ions in electrolyte move to cathode/anode?
electrolysis
anions -> negatively charged cathode
cations -> positively charged anode
simple cell
cations -> positively charged cathode
anions -> negative charged anode
what is discharge
lose charge
i.e. cation
Na+ (l) + e- -> Na (l)
molten
metal element
forms on surface of water
globules of silvery metal forms
h2o (l) electrolysis
no reaction
h2o(l) does not have ions
H+, Oh- ions only present, ionic compound (aq)
In very conc. soln (aq)
will number of Cl- > Oh-
no
- Cl- ions will nvr outnumber Oh-
- Oh- is solvent
- in conc. soln, no of Cl- ions is more than usual
which anions are not affected by conc. (anode)?
what happens instead?
- So4 2-, No3 -
- even when conc. ___ sulfate/nitrate Oh- will be selectively discharged
anyth w/ ions can be discharged i.e. acid/alkali
Oh- discharged half eqn
4OH- (aq) -> 2H2o (l) + O2 (g) + 4e-
keep in mind
OH- ions is in water when other ions present.
water (l) (pure water) // water with no ions dont have Oh-
for visible observation for electrolysis…
- any solid formed
- color change of soln.
- efferverscence + gas released
DO NOT write water level rise/drop
industrial use, electrolysis
besides extraction, metals
- electrolytic purification
- electroplating
desc electroplating process, anode, cathode, electrolyte
- coat metal with a layer of another metal
- anode: pure plating metal
- cathode: plated obj (must b conductor of electricity)
- electrolyte: (aq) soln. (nitrate), salt of plating metal
anode metal, if non-reactive (Not Pt, graphite), tends to diminishes in size
cathode metal tends to thicker in size
electrolytic purification
- purify metals, Cuso4
- anode (impure metal)
- cathode (pure metal)
in electrolysis, which is anode, cathode?
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit?tab=t.0 page 14
cathode mostly goes by react. series but always use logical reasoning abt what the set up is for
if there is battery connected to voltmeter
is setup electrolysis/simple cell?
electrolysis
AS LONG AS THERE IS BATTERY
Simple cell
- when is more electricity generated?
- when is no electricity generated?
- difference between reactivity of both electrodes is greater
- two same metals in simple cell, same reactivity, no difference in reactivity, hence no voltage generated
voltmeter will also read
simple cell
which metals dont use?
ones higher up in reactivity series
Potassium, Sodium
what are fuel cells
chemical cell in which reactants are continuously supplied, produce electricity directly
i.e. hydrogen-oxygen fuel cell
fuel cell vs simple cell
fuel cell: electrodes are same material
fuel cell vs dry cell
reactants are pumped in,
not contained within
fuel cell
anode and cathode half eqns
anode: 2H2(g) + 4OH- (aq) -> 4H2o (l) + 4e-
cathode: 2H2o(l) + O2 (g) + 4e- -> 4OH- (aq)
how does fuel cell work
electrons drawn from anode -> cathode through eternal circuit, produce direct current
electroplating usages
- metals more resistant, corrosion
i.e. chromium, nickel plating - improve appearance, metals
i.e. coat cutlery, jewelry w/ silver
