reactivity series metals alloys rusting electrolyisis Flashcards
reactivity series
K
Na
Li
Ca
Mg
Al
C
Zn
Fe
H
Cu
Ag
Au
react with water
K Na Li Ca
metal + water > metal hydroxide + hydrogen
potassium + water
> potassium hydroxide + hydrogen
- effervescence
- moves on surface of water
- melts into ball
- lilac flame
sodium + water
> sodium hydroxide + hydrogen
- effervescence
- moves on surface of water
- melts into ball
lithium + water
> lithium hydroxide + hydrogen
- effervescence
- moves on surface of water
calcium + water
> calcium hydroxide + hydrogen
- effervescence
- forms white precipitate
react with acids
Mg Zn Fe
metal + acid > salt + hydrogen
magnesium + hydrochloric acid
> magnesium chloride + hydrogen
- effervescence
- moves on surface
- disappears
zinc + hydrochloric acid
> zinc chloride + hydrogen
- effervescence
iron + hydrochloric acid
> iron chloride + hydrogen
- effervescence
copper + hydrochloric acid
no reaction
don’t react with acids or water
Cu Ag Au
(use displacement reactions to order them)
displacement reaction
use to see which metal is more reactive
- in terms of O2
oxidation - gain O2
reduction - loss O2
- in terms of e-
oxidation - loss e-
reduction - gain e-
magnesium + copper oxide
Mg + CuO
(displacement example - from metal oxide)
> magnesium oxide + copper
MgO + Cu
- bright white light
- exothermic
Cu displaced by Mg
Mg > oxidised (gain O2)
CuO > reduced (lost O2)
Mg is more reactive than Cu
magnesium + copper sulphate
Mg + CuSO4
(displacement example - from aq solution)
magnesium sulphate + copper
MgSO4 + Cu
- solution becomes paler
- pink brown solid disappears
Cu is displaced by Mg
Mg > oxidised (lost e-)
Cu2+ > reduced (gain e-)
Mg is more reactive than Cu
extracting metals
with carbon
electrolysis
metal ore
rocks that contain enough metal in a compound to be economical to extract
(metals can be extracted from their ore)
extracting with carbon
- used for metals less reactive than carbon
- heat with C/ CO - displaces metal from ore
eg 2CuO + C > CO2 +2Cu
C - oxidised - reducing agent
CuO - reduced
extracting by electrolysis
- used for metals more reactive than carbon
- expensive so carbon is preferable if it can be used
- uses lots of electricity
pure metals - bonding/properties
- metallic bonding - EA between cations and sea of delocalised electrons
- conducts elec- delocalised electrons free to move throughout structure
- malleable - layers of ions can slide over each other
alloy
mixture of metals with another metal or carbon - harder than pure metal
why is allot harder than pure metal?
- consists of diff. sized atoms
- layers distorted
- layers can no longer slide over each ither
alloy examples
sterling silver
bronze
brass
18k gold
steel
steel
alloy of iron and carbon
4 types
- cast iron
- low carbon
- high carbon
- stainless steel
cast iron
- hard - brittle - can’t be compressed
- stoves - drains - engines
low carbon steels
- easily shaped
- car body panels - domestic goods
high carbon steels
- hard
- cutting tools
stainless steel
- hard - strong - resistant to corrosion
- cutlery - sink - tools
iron uses
- machinery
- tools
- bridges
- car bodies
- engines
- cutlery
- sink
iron properties
- hard+tough
- can be rolled into sheets and cut
aluminium uses
- aircraft
- trains
- power cables
- saucepans
- cooking foil
aluminiums properties
- conducts heat
- connects electrons
- malleable
- high mtp.
- low density
- resist corrosion
copper uses
- electrical cabling
- plumbing pipes
copper properties
- conducts heat
- conducts electricity
- malleable
- high mtp.
- ductile
- unreactive
rust
corrosion of iron (+steel)
conditions required for ruse
- oxygen
- water
(salt - speeds up rusting)
sacrificial protection
coat iron with a more reactive metal (reacts + looses electrons instead of iron so corrodes instead)
eg Mg
eg Zn - galvanisation
anode
+ charged
anions moves to anode (opposite charges attract)
cathode
- charge
cation moves to cathode (opposite charges attract)
electrolyte
substance that under goes electrolysis (must conduct)
molten or aq - so ions are free to move
electrolysis of molten lead bromide
heated to molten so ions can move
cathode - orange gas bubbles - oxidation
2Br- (l)>Br2 (g)+ 2e-
anode - dark grey liquid - reduction
Pb2+ (l) + 2e- > Pb(l)
test of hydrogen
lit splint
squeaky pop
test for oxygen
glowing splint
relight
OILRIG
oxidation is loss reduction is gain
PANIC
Positive anode negative is cathode
corrosion
metals react with substances in air
rust equation
iron + water + oxygen > hydrated iron oxide
rust prevention
physical barriers
sacrificial protection (galvanisation)
physical barriers
prevent iron coming into contact with water and oxygen in air
eg paint plastic oil
galvanisation
iron is coated with zinc
Zn is more reactive so oxidised in preference to iron
electrolysis
splitting of a compound into its elements using electricity
electrodes
conduct electricity
high mtp.
unreactivity
usually platinum /graphite
electrolysis of aqueous sodium chloride
cathode - H+, Na+ - colourless gas - 2H+ + 2e- > H2
anode - OH- Cl- - pale green gas - 2Cl- > Cl2 + 2e-
electrolysis of water
H2O > H+ + OH-
- anode - 4OH- > 2H2O + O2 + 4e- bubbles of O2 - relights glowing splint
- cathode - 2H+ +2e- > H2 - bubbles of H2 - lit splint squeaky pop
- 2H2O > 2H2 + O2 (2H:O)
aq - which ion will be discharged- cathode
least reactive is discharges (reduced)
aq - which ion will be discharged anode
halides always discharged if not a halide then hydroxide will be discharged
(halide than hydroxide then anything else)
mnemonic
Please
Send
Lions
Cats
Monkeys
And
Cool
Zebras
Into
Hot
Countries
Sincerely
Gordon
