Karteikarten
Metals and Acids
Karten in diesem Stapel (23)
- 1Metals - OVERVIEWAll metals have the same basic properties
SPECIAL TYPE OF BONDING - giant structure of atoms held together with metallic bonds
OUTER ELECTRON(S) of each atom can MOVE FREELY
= SEA OF FREE ELECTRONS - 2Properties of metalsAll conduct electricity - free electrons carry the current
All conduct heat - free electrons carry heat energy
Strong BUT
Malleable (can be hammered/bent into shape)
Shiny (when freshly cut/polished)
Have high melting/boiling points e.g. copper 1100ºC
Can be mixed to form ALLOYS
e.g. steel (iron + 1% carbon)
e.g. bronze (copper + tin) - 3Non-MetalsNon-metals are either dull, brittle solids or gases
About a 1/4 of the elements are non-metals
Half the non-metals - GASES
Half the non-metals - SOLIDS
BROMINE - only liquid non-metal - 4Properties of non-metalsPoor conductors of heat
Don't conduct electricity (except graphite - has free electrons to a=carry electrical charge between layers)
Usually bond in small molecules
EXCEPT SILICON AND CARBON e.g. diamond =giant structure of carbon - 5Reactions of ALKALI metals with waterLITHIUM, SODIUM, POTASSIUM = very vigorous reaction (move around surface + fizz)
Produces HYDROGEN
Squeaky pop = presence of hydrogen - 6Reactions of alkali metals in airPRODUCES OXIDES
Burn with different coloured flames
e.g. lithium = red flame
sodium = orange flame
potassium = lilac flame - 7Acids reacting with metalsMETAL + ACID = SALT + HYDROGEN
(MASH) - 8The Reactivity SeriesPotassium K
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
(Carbon)
Zinc Zn
Iron Fe
Lead Pb
(Hydrogen)
Copper Cu
Silver Ag
Gold Au
Platinum Pt
3 reactions to determine reactivity: with air, water, dilute acid - 9Reacting metals with WATERWILL ALWAYS RELEASE HYDROGEN
MORE reactive metals react with cold water to form HYDROXIDES
E.g. Sodium + water -> sodium hydroxide + hydrogen
LESS reactive metals react slowly and form OXIDES
E.g. Zinc + water -> zinc oxide + hydrogen
Potassium, sodium, calcium - react with cold water
Magnesium, aluminium, zinc - react with steam
Iron - reacts reversibly with steam
Lead, copper, silver, gold - no reaction with water/steam - 10Reacting metals in AIRDull finish on surface of metals - due to a layer of OXIDE that forms (surface of metal exposed to oxygen)
METAL + OXYGEN -> METAL OXIDE
E.g. 2FE + O2 -> 2FEO
Potassium, sodium, calcium, magnesium - burn very easily with bright flame
Aluminium, zinc, iron, lead, copper - react slowly with air when heated
Silver, gold - no reaction - 11Reacting metals with DILUTE ACIDSMetals ABOVE HYDROGEN react with ACIDS
Metals BELOW HYDROGEN do NOT
Further down the reactivity series = slower reactions
METAL + ACID -> SALT + HYDROGEN
Mg + 2HCL -> MgCl2 +H2
Potassium, sodium, calcium - violent reaction with dilute acids
Magnesium, aluminium, zinc, iron - fairly fast reaction
Lead, copper, silver, g0ld - no reaction - 12Competition ReactionsMetal reactions with acids and water = competition reactions
If the metal is MORE REACTIVE than hydrogen the hydrogen is pushed out (bubbles on surface)
The metals REPLACES the hydrogen in the compound - hydrogen released as gas bubbles
If the metal is LESS REACTIVE than hydrogen there is NO REACTION - 13Displacement Reactions'A MORE reactive metal will displace a LESS reactive metal from a compound'
Some metals react more strongly than others (refer to reactivity series)
If you add a reactive metal to a dissolved chemical compound, the MORE reactive metal will REPLACE the LESS reactive metal in the compound
The "kicked out" metal will appear as a FRESH METAL in the solution
If the metal that is added to the solution is less reactive than the one already in the solution there will be NO REACTION - 14Metals OresMetals are extracted from their ores using CARBON or ELECTROLYSIS
Involves a chemical reaction to separate the metal
Sometimes metals can be found in ores as OXIDES
3 ores to know:
1) Iron ore = 'Haematite' - iron (111) oxide - Fe2O3
11) Aluminium ore = 'Bauxite' - aluminium oxide - Al2O3
111) Copper ore = 'Malachite' - copper (11) carbonate - CuCO3
2 COMMON WAYS OF EXTRACTING A METAL:
1) Chemical reduction using carbon/carbon monoxide
2) Electrolysis - 15CARBON in the reactivity seriesMetals HIGHER than carbon are extracted using ELECTROLYSIS
Metals BELOW carbon are extracted by REDUCTION using CARBON (takes the oxygen out of the metals that are less reactive than it) - 16Extracting Iron - THE BLAST FURNACE (+ equations needed)Iron - very common element
Extracted from HAEMATITE (Fe2O3) by process of REDUCTION (is below carbon in reactivity series)
RAW MATERIALS:
Iron ore - contains iron
Coke - almost pure carbon (reduced iron oxide to iron metal)
Limestone - takes away IMPURITIES in the form of SLAG
1) Hot air blasted into furnace - makes COKE burn MUCH FASTER than normal (temperature rises to about 1500ºC)
2) Coke burns and produces CO2
Carbon + oxygen -> carbon dioxide
C + O2 -> CO2
3) The CO2 reacts with UNBURNT COKE to form CO
Carbon dioxide + carbon -> carbon monoxide
CO2 + C -> 2CO
4) The carbon monoxide reduced the IRON ORE to IRON (useful metal)
Carbon monoxide + iron (111) oxide -> carbon dioxide + IRON
5) Iron is in a MOLTEN STATE - very dense (runs to the bottom of the blast furnace where is it TAPPED OFF) - 17The Blast furnace 2 Removing impurities (+ equations)Removing the impurities:
Main impurity - SAND (silicon dioxide) still a solid even at 1500ºC!! - stays mixed with the iron
THE SAND IS REMOVED BY LIMESTONE
1) Limestone is DECOMPOSED by the heat into calcium oxide and CO2
Limestone -> calcium oxide and carbon dioxide
CaCO3 -> CaO + CO2
2) The calcium oxide reacts with the sand to form CALCIUM SILICATE (slag - molten, can be tapped off)
Calcium oxide + silicon dioxide (sand) -> Calcium silicate (molten slag)
CaO + SiO2 -> CaSiO3
3) The slag cools - becomes a SOLID (can be used for roads, fertiliser) - 18Uses of common metals (iron/steel, aluminium, copper)IRON (can be made into steel)
Advantages: cheap, strong
Disadvantages: heavy, corrodes (rusts)
Used for: bridges, buildings, cars, boats
Stainless steel: DOESN'T RUST - used for pans
ALUMINIUM
Advantages: Lightweight (low density)
Can be shaped
Strong
DOESN'T RUST
CONDUCTS heat and electricity
Disadvantages: not as strong as steel, expensive
Uses: planes, ladders, drink cans
COPPER
Advantages: good conductor of electricity
doesn't rust
can be bent
Disadvantages: expensive
not very strong
Uses: water/gas pipes
electrical wiring
form NON CORRODING alloys (brass - used for instruments) - 19CORROSION (rusting) of metalsReactive metals will form OXIDES when they are exposed to air (oxygen)
Oxides = hard protective layer
E.g. ALUMINIUM - forms aluminium oxide (very hard coating) = aluminium is very unreactive BUT without it's protective oxide layer it's VERY REACTIVE
BUT iron doesn't form a good, hard oxide layer...
It forms hydrated iron (111) oxide - or rust (a flaky red oxide) - 20PREVENTING rustRusting is prevented by...
PAINT - however, if paint surface gets damaged rust will spread
OIL - however, has to be constantly re-applied because it washes off
GALVANISING - best method
process: Bonds a layer of zinc metal onto the surface of the steel. The zinc reacts with the with air to form ZINC OXIDE (good protective layer)
advantages: even if the zinc coating gets damaged the exposed steel will NOT rust (zinc reacts instead)
...known as SACRIFICIAL PROTECTION
- a MORE reactive metal (zinc) in contact with a LESS reactive metal (steel/iron) will react first = PROTECTING the LESS reactive metal from corrosion - 21TRANSITION metalsIN THE MIDDLE OF THE PERIODIC TABLE
CHROMIUM, MANGANESE, IRON, NICKEL, COPPER, ZINC - 22Transition metals - PROPERTIESTypical metals - possess the same qualities as normal metals:
All have high melting point/density
Conduct heat/electricity
Dense, strong, shiny
All make good CATALYSTS
Their COMPOUNDS are colourful (contain transition metals)
Often have MORE THAN ONE ION - 23Transition metals - USESIRON - manhole covers (pure iron = very brittle)
COPPER - electrical wiring/ water pipes
Zinc - used to GALVANISE IRON
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- Karteikarten am Metals and Acids, erstellt von Ailis am 08/04/2015.
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