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C7/5 chemical energetics/C9metals - Coggle Diagram
C7/5 chemical energetics/C9metals
energy
given out by reactions
natural gas(mainly methane) used for heat
hydrocarbon contain only carbon and hydrogen, methane is simplest
CH4+2O->CO2+2H2O
exothermic(raise temperature of surroundings)
in reactions bonds are broken and new ones are made
to break takes energy, endothermic
to make
lower temperature of surroundings
N2(nitrogen)+O2->2NO(nitrogen monoxide)
energy level diagram, energy KJ, progress
reaction only happens if total energy of the colliding particles > required activation energy
heat of combustion
for liquid fuels, use metal calometer & spirit burner
heat known volumn of water with flame from (fuel), the temperature rise is measured(water)
the heat energy can be worked out knowing the amount of fuel
rate of reaction
rusting is slow, explosions are
surface area, concentration, temperature, catalyst, light(if needed)
for solids, more powdered has bigger surface area, more rate
more mixed the powdered reactants, better contact and better rate
catalyst
many catalyst provide a surface area for the chemical reaction while not taking part
some work different and some do take place
but stay same amount and chemically unchainged
metals
group 1 alkali metals(similar proprieties)
react with cold water
melting points, reactivity and hardness decrease as go down
alkali metal+water->sodium hydroxyde+hydrogen
all alkali metal ions give different color in flame
group 2 alkaline earth metals
down, more reactivity
magnesium burns white
2Mg+O2->2MgO
Mg+H2O->MgO(magnesium oxide)+H2
aluminium
alluminium chloride(AlCl3)+sodium(3Na)->sodium chloride(3NaCl)+aluminium(Al)
alkali metals(colored compounds
copper(II)Cu2+ blue, iron(II) Fe2+ green, iron(III) red-brown,
cause color in gemstones etc
transition elements group 3-10
less reactive than groups 1,2
few are magnetic
iron+hydrocloric acid(2HCl)->iron(II)chloride(FeCl2)+H2
2Cu+O2-heat->2CuO(copper(II)oxide)
copper(II)carbonate(CuCo3)->copper(II)oxide+CO2
same with zinc(Zn)
metal reactions
electrolysis extraction
metals more reactive than carbon must use electrolysis
copper, silver and gold, unreactive enouph to appear uncombined underground
more reactive appear as ores and need reduction with carbon
displacement reaction
more reactive displaces less reactive
Zn+CuSo4(copper sulfate)-->ZnSO4+Cu
zinc metal is coated in red-brown layer of copper, solution becomes colorless ZnSO4
reactive metals are good reducing agents
zinc(Zn)+copper(II)ions(Cu2+)->zinc ions(Zn2+)+Cu
redox reaction: transfer of two electrons from zinc atoms to copper(II)ions
zinc atoms oxidised, copper(II)ions reduced
atoms of more reactive metal lose electrons to become + ions