chap1, form 5 Flashcards
oxidation: oxygen
gain
oxidation: hydrogen
lose
oxidation: oxidation number
increase
oxidation: electron
lose
U-TUBE: how many substances are at +ve terminal
6
U-TUBE: what are the substances at +ve terminal
KMnO4 K2Cr2O7 Cl2 Br2 FeCl3 H2O2 KKCaukeBangladeshForHenry
U-TUBE: how many substances are at -ve terminal
6
U-TUBE: what are the substances at -ve terminal
KI KBr reactive metals FeSO4 SO2 KKRempitForSofia
what are reactive metals not used in u-tube
Cu and Ag
colour change of Fe2+
green to yellow
colour change of Fe3+
orange to brown
colour of Cu2+
blue
colour change of KMNO4
purple to colourless
colour change of K2Cr2O7
orange to green
colour change of Cl2
greenish yellow to colourless
colour change of Br2
orange to colourless
colour change of FeCl3
yellow to green
colour change of KI
colourless to yellow
colour change of KBr
colourless to orange
colour change of FeSO4
green to yellow
function of salt bridge
allow movement of ions between electrolytes
function of galvanometer
shows transfer of electrons
function of arrow
shows movement of electrons
U-TUBE: what happens at positive terminal
reduction
U-TUBE: what happens at negative terminal
oxidation
what are the 2 displacement reactions?
halogen displacement
metal displacement
in halogen displacement, it involves which group?
group 17
how is the reactivity in G17?
going down group, reactivity decreases
how do you know its a halide?
it has -ides at the back
what is the strongest oxidising agent in G17?
flouride
what is the strongest reducing agent in G17?
astatide
why does the blue colour of copper nitrate become paler?
the concentration of Cu2+ ion decreases
colour of copper metal
brown
ECS gimme the order
kalau kahwin nak, mesti ada zakat fitrah supaya perkahwinan helok kekal abadi
what is the EO value of H2
0 V
all metal ions are __ agent
oxidising
all metals are ___agent
reducing
what is the strongest oxidising agent in ECS?
silver ion
what is the strongest reducing agent in ECS?
potassium, K
what happens at cathode?
reduction
what happens at anode?
oxidation
arrangement of cell notation for voltaic cell
anode: cathode
metal/metal ion/metal
how to find E0 of cell
if given +ve and -ve terminal
E0(+ve terminal) - E0(-ve terminal)
how to find E0 of cell
if given cathode and anode
E0 cathode - E0 anode
what is the energy change that happens in voltaic cells?
chemical energy to electrical energy
function of voltaic cell
to supply electrical energy
ionic equation of anode depends on?
type of metal
how to determine which metal at anode? what are the requirements?
more reactive metal
how to determine which metal at cathode? what are the requirements?
less reactive metal
ionic equation of cathode depends on?
electrolyte
in electrolytic cell, the anode is connected to the ___terminal of battery
positive
in electrolytic cell, the cathode is connected to the ___terminal of battery
negative
in electroplating, at cathode what is put there?
the object plated
in electroplating, at anode what is put there?
metal for electroplating
in purification of metals, at cathode what is put there?
pure metal OR pure copper
in purification of metals, at anode what is put there?
impure metal OR impure copper
cathode attracts
cation
anode attracts
anion
for inert electrodes, what metals are used?
carbon, platinum
definition of electrolysis
a process where compounds in molten state or aqueous decompose into their constituent elements by passing electricity through them
what is energy change at electrolytic cell
electrical energy to chemical energy
for cathode, take cation with ___ E0 value
more positive
for anode, take anion with ____E0 value
less positive
if there is presence of hydrogen, oxygen gas what is the observation?
bubbles/effervescence
if there is presence of copper what is the observation?
brown deposition
if there is presence of silver, iron what is the observation?
shiny metal deposition
if there is presence of bromine gas what is the observation?
brown gas
if there is presence of lead what is the observation?
grey solid formed
electrolyte of electroplating contains what?
cations similar to anode
what is observation at cathode for electroplating?
shiny metal on surface of object
what is observation at anode for electroplating?
size of metal electrode has decreased
why is there shiny metal on surface of object?
there is metal coating on the object
why has the metal electrode decreased?
the electrode has deionised to release its ions in the electrolyte
for smooth coating of object, use ___electrical energy
low voltage
for smooth coating of object, _____slowly for ___
rotate object
even distribution of metal on object
for smooth coating of object,
____of object with ___
clean surface
sand paper to remove oxide layers before electroplating
what are the 2 insoluble carbonate salts?
silver carbonate
copper(II) carbonate
what is the 1 insoluble chloride salt?
silver chloride
electrolyte of purification of metal has to be ____ with metal being purified
same
if copper was being purified, what electrolytes can be used? give 3
aqueous
CuSO4
CuCl2
Cu(NO3)2
carbon lining in extraction of aluminium act
as
cathode
carbon/graphite electrodes in extraction of aluminium as
anodes
what is solution used in extraction of aluminium
molten aluminium oxide in molten cryolite
aluminium is extracted from
aluminium oxide or alumina
aluminium oxide is the purified version of?
bauxite or aluminium ore
what gas is released during extraction?
CO2
purification of bauxite creates
toxic red sludge
why does molten aluminium sink to the bottom?
high density
extraction of aluminium: what is the observation at cathode?
shiny deposition
extraction of aluminium: what is the observation at anode?
bubbles
why are there bubbles at anode?
there is presence of oxygen gas
why is there shiny deposition at cathode?
aluminium
3 function of cryolite
to lower melting point of bauxite from 2000 to 700
speed up production
reduce electrical cost
extraction of iron from hematite: what is added at the top? name 3
iron ore, coke, CaCO3
hematite chemical formula
Fe2O3
blast furnace used in
extraction of iron from hematite
extraction of iron from hematite: why hot air is supplied in? give 2 reasons.
increase rate of reaction
less dense, so it move upwards to react with materials up there
slag aka
CaSiO3
density of slag
less dense than molten iron
what is reduced in carbon reduction process?
iron(III) oxide reduced
what happens in zone 1?
oxygen reacts with coke to form CO2
what happens in zone 2?
CO2 reacts with coke to form CO
what reduces iron(III) oxide to iron?
coke or CO
function of calcium carbonate/limestone?
decompose to form CaO/quicklime
function of CaO
neutralise and react with SiO2 to form CaSiO3
2 factors need for rusting
water, oxygen
rate of rusting is high in 2 situations. give them
high temperature
salt/acid solution
why is the rate of rusting high in salt/acid solution?
there are free moving ions
explain how rusting of metal is a redox reaction
metal is oxidised spontaneously when metal atoms release electrons to form metal ions
the ___electropositive metal the easier to ____
more
corrode
where is anode in rusting?
the very bottom yalls
what happens at anode in rusting?
iron ionises to become Fe2+
where is cathode in rusting?
at the very edge of droplet
what happens in cathode in rusting?
oxygen and water gain 4 electrons to form OH ion
how to indicate hydroxide ion in phenolphtalein?
pink
what happens after OH ion is formed?
the OH ion combine with Fe2+ to form iron(II) hydroxide
then what happens after iron(II) hydroxide is formed?
the iron(II) hydroxide will continue to react with oxygen to form rust
chemical name for rust?
hydrated iron (III) oxide
chemical formula for hydrated iron (III) oxide?
Fe2O3 x H2O
definition of galvanisation
a layer of zinc galvanises steel or iron
definition of tin plating/stanum
a layer of tin electroplates steel
characteristic of oxide layer
hard, non porous
another method to prevent rust starts with C
chrome plating
definition of sacrificial protection
iron is attached to a more electropositive metal
what happens to the more electropositive metal in ?sacrificial protection
it eventually corrodes, sacrificed