CHEMISTRY OCR GATEWAY C1

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C1A - Making Crude Oil Useful

FOSSIL FUELS

COAL, OIL, GAS - NOT RENEWABLE AS THEY TAKE A LONG TIME TO MAKE - FINITE RECOURCE (WILL RUN OUT)

FRACTIONAL DISTILLATION OF CRUDE OIL

  • CRUDE OIL FORMED FROM BURIED REMAINS OF PLANTS AND ANIMALS WHICH TURN TO CRUDE OIL OVER MILLIONS OF YEARS WITH HIGH TEMPERATURE AND PRESSURE - FOSSIL FUEL
  • MIXTURE OF LOTS OF HYDROCARBONS (CHAONS OF CARBON ATOMS OF VARIOUS LENGTHS)
  • DIFFERENT COMPOUNDS OF CRUDE OI SEPERATED OUT BY FRACTIONAL DISTILLATION - OIL IS HEATED AND MOST TURNS TO GAS - ENTERS FRACTIOATING COLUMN WHERE THERE IS A TEMPERATURE GRADIENT (HOT AT THE BOTTOM AND GETS GRADUALLY COOLER TOWARDS THE TOP)
  • THE ONLY SUBSTANCE THAT DOES NOT TURN TO GAS IS BITUMIN, WHICH STAYS LIQUID AND GETS DRAINED OFF AT THE BOTTOM OF THE COLUMN
  • THE SHORTER THE HYDROCARBONS THE LOWER THEIR BOILING POINTS SO THE LONGER HYROCARBONS STAY AT THE BOTTOM
  • END UP WITH CRUDE OIL MIXTURE SEPARATED OUT INTO DIFFERENT FRACTIONS, CONTAINING A MIXTURE OF HYDROCARBONS WITH SIMILAR BOILING POINTS
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C1A - Making Crude Oil Useful

(http://3.bp.blogspot.com/-gqGIhxOJ3bE/UDsoo5u9ibI/AAAAAAAAAH8/Nn7c1COjqy8/s1600/fractioning_column.jpg)

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C1A - Making Crude Oil Useful

HYDROCARBON BONDS

  • AS THE SIZE OF THE HYDROCARBON MOLECULE INCREASES:
  • THE BOILING POINT INCREASES
  • IT GETS LESS FLAMMABLE
  • IT GETS MORE VISCOUS (DOESN'T FLOW AS EASILY)
  • IT GETS LESS VOLATILE (DOESN'T EVAPORATE AS EASILY)
  • TYPES OF BONDS IN CRUDE OIL: STRONG COVALENT BONDS WHICH HOLD THE HYDROGENS AND CARBONS WITHIN EACH HYDROCARBON MOLECULE TOGETHER AND THE INTERMOLECULAR FORCES OF ATTRACTION BETWEEN EACH HYDROCARBON MOLECULE
  • COVALENT BONDS ARE MUCH STRONGER THAN THE INTERMOLECULAR FORCES, SO THEY DON'T BREAK WHEN CRUDE OIL IS HEATED.
  • THE LONGER THE HYDROCARBON CHAIN, THE STRONGER THE INTERMOLECULAR FORCES - BREAK A LOT LESS EASILY - HIGHER BOILING POINT
  • THIS IS WHY LONG CHAIN HYDROCARBONS STAY AT THE BOTTOM OF THE DISTILLATION COLUMN AS LIQUIDS
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C1A - Making Crude Oil Useful

CRACKING - SPLITTING UP LONG CHAIN HYDROCARBONS

  • TURNS LONG ALKANE MOLECULES INTO SMALLER ALKANE AND ALKENE MOLECULES - FORM OF THERMAL DECOMPOSITION - MEANS BREAKING STRON COVALENT BONDS - LOTS OF HEAT AND A CATALYST NEEDED
  • LONGER MOLECULES PRODUCED FROM FRACTIONAL DISTILLATION ARE CRACKED INTO SMALLER ONES - MORE DEMAND FOR SHORTER CHAIN MOLECULES LIKE PETROL
  • ALSO PRODUCES ALKENE MOLECULES - CAN BE USED TO MAKE POLYMERS

CONDITIONS NEEDED FOR CRACKING

VAPORISED HYDROCARBONS PASSED OVER A POWDERED CATALYST (ALUMINIUM OXIDE) AT ABOUT 400 - 700 DEGREES CELCIUS

(http://2.bp.blogspot.com/_Nn7AL_BBoy4/TFO3_IrQ6pI/AAAAAAAAAFI/CpV2amAAZiU/s1600/cracking.jpg)

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C1A - Making Crude Oil Useful

POLITICAL PROBLEMS

  • AS FOSSIL FUELS GET USED UP, THEY WILL GET MORE EXPENSIVE - COUNTRIES WITH BIG STOCKS OF OIL MIGHT START KEEPING IT FOR THEIR OWN USE INSTEAD OF SELLING IT
  • COUNTRIES WITH THE MOST OIL AND GAS WILL HAVE POWER OVER OTHER COUNTRIES - COULD CAUSE CONFLICT
  • HARDER FOR COUNTRIES WITHOUT A LOT OF SUPPLY TO GET HOLD OF IT - MIGHT HAVE TO DEPEND ON POLITICALLY UNSTABLE COUNTRIES FOR SUPPLIES - COULD BE CUT OFF AT ANY TIME

ENVIRONMENTAL PROBLEMS

  • OIL TANKER CRASHES CAN LEAD TO HUGE AMOUNDS OF CRUDE OIL BEING RELEASED INTO THE SEA - OIL FLOATS ON WATER AND IS SPREAD OUT INTO HUGE OIL RIGS
  • COVERS SEA BIRDS FEATHERS AND STOPS THEM FROM BEING WATERPROOF - WATER SOAKS INTO FEATHERS AND THEY DIE OF COLD
  • ANIMALS WON'T BE ABLE TO FLY BECAUSE FEATHERS ARE MATTED WITH OIL
  • DETERGENTS ARE OFTEN USED TO CLEAN UP OIL SLACKS (BREAK OIL INTO TINY DROPLETS, MAKING IT EASIER TO DISPENSE) - SOME HARM WILDLIFE
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C1B - Using Carbon Fuels

USE OF CRUDE OIL

  • PROVIDES ENERGY NEEDED TO DO LOTS OF THINGS E.G. HEATING HOMES, GENERATING ELECTRICITY
  • PROVIDES FUEL FOR MOST MODERN TRANSPORT
  • PROVIDES RAW MATERIALS NEEDED TO MAKE CHEMICALS LIKE PLASTIC
  • POPULATION INCREASE, INDIA AND CHINA GETTING MORE DEVELOPED - MORE DEMAND FOR FOSSIL FUELS - FOR INCREASED HOME USE AND TO RUN MANUFACTURING INDUSTRIES
  • SUPPLIES LIMITED AND NON RENEWABLE - ONE DAY THEY'LL RUN OUT
  • NEW TECHNOLOGY MEANS THAT WE CAN GET FUELS THAT WERE ONCE UNREACHABLE
  • WE SOULD START THINKING ABOUT NEW ENERGY SOURCES LIKE SOLAR AND WIND POWER
  • SOME PEOPLE THINK WE SHOULD STOP USING OIL FOR FUEL (WHERE WE HAVE ALTERNATIVES) AND SAVE IT FOR MAKING POWER SO THAT IT WILL LAST LONGER
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C1B - Using Carbon Fuels

FACTORS TO CONSIDER WHEN CHOOSING THE BEST FUEL

  • ENERGY VALUE - HOW MUCH ENERGY IS RELEASED FROM A CERTAIN AMOUNT OF FUEL
  • AVAILABILITY - WHETHER YOU CAN GET HOLD OF IT EASILY
  • STORAGE - MAY BE DIFFICULT TO STORE SAFELY IF FLAMMABLE OR EXPLOSIVE
  • COST - VALUE IN TERMS OF ENERGY CONTENT
  • TOXICITY - MAY RELEASE POISONOUS FUMES WHEN BURNED
  • EASE OF USE - LIGHTS EASILY, MOVES SAFELY
  • POLLUTION - MAY ADD TO ACID RAIN AND GREENHOUSE EFFECT
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C1B - Using Carbon Fuels

COMPLETE COMBUSTION

  • HYDROCARBON + OXYGEN -----> CARBON DIOXIDE + WATER (+ ENERGY)
  • RELEASES LOTS OF ENERGY AND PRODUCES ONLY CARBON DIOXIDE AND WATER AS WASTE PRODUCTS - CLEAN AND NON POISONOUS
  • GAS HEATERS RELEASE WASTE GASES INTO ROOM - SAFE IF GAS HEATER IS WORKING PROPERLY AND ROOM IS WELL VENTILATED
  • LOTS OF OXYGEN - COMBUSTION COMPLETE - GAS BURNS WITH CLEAN BLUE FLAME
  • CH4 +2O2 -----> 2H2O + CO2

EXPERIMENT FOR SHOWING WASTE PRODUCTS OF COMPLETE COMBUSTION

  • WATER PUMP DRAWS GASES FROM BURNING HEXANE THROUGH APPARATUS
  • WATER COLLECTS INSIDE COOLED U TUBE (SHOW THAT IT'S WATER BY CHECKING BOILING POINT)
  • LIME WATER TURNS MILKY, SHOWING THAT CARBON DIOXIDE IS PRESENT.
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C1B - Using Carbon Fuels

INCOMPLETE COMBUSTION

  • HYDROCARBON + OXYGEN -----> CARBON DIOXIDE +WATER + CARBON MONOXIDE + CARBON (+ENERGY)
  • OCCURS WHEN THERE IS NOT ENOUGH OXYGEN PRESENT TO GIVE CARBON MONOXIDE AND CARBON AS WASTE PRODUCTS - PRODUCES SMOKEY YELLOW FLAME
  • CARBON DIOXIDE - COLOURLESS, ODOURLESS, POISONOUS GAS - VERY DANGEROUS 
  • IF BOILER BREAKS AND ROOM IS FILLED WITH CARBON MONOXIDE - KILLS PEOPLE AS NO ONE REALISES WHEN CARBON MONOXIDE IS PRESENT - NO COLOUR OR ODOUR
  • 4CH4 + 6O2 -----> C + 2CO + CO2 + 8H2O (+ ENERGY)

 

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C1C - Clean Air

THE EVOLUTION OF THE ATMOSPHERE

PHASE 1 - VOLCANOES GAVE OUT STEAM AND CO2

  • EARTHS SURFACE WAS ORIGINALLY MOLTEN FOR MILLIONS OF YEARS - ANY ATMOSPHER BOILED AWAY
  • EVENTUALLY COOLED - THIN CRUST FORMED - VOLCANOES ERRUPTED, RELEASING GASES FROM INSIDE EARTH - MAINLY CARBON DIOXIDE - ALSO STEAM AND AMMONIA

PHASE 2 - GREEN PLANTS EVOLVED AND PRODUCED OXYGEN

  • EARLY CO2 DISSOLVED INTO OCEANS - GREEN PLANTS EVOLVED AND PHOTOSYNTHESISED, USING UP CO2 AND PRODUCING O2
  • AMOUNT OF 02 IN AIR GRADUALLY BUILT UP AND MUCH CO2 WAS LOCKED UP IN FOSSIL FUELS AND SEDIMENTARY ROCKS
  • NITROGEN GAS PUT INTO AIR - FORMED BY AMMONIA REACTING WITH OXYGEN AND RELEASED BY DENITRIFYING BACTERIA
  • NITROGEN NOT REACTIVE - SMALL AMOUNT IN AIR INCREASED BECUASE IT WAS BEING CREATED AND NOT MUCH WAS BEING BROKEN DOWN
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C1C - Clean Air

PHASE 3 - OZONE LAYER ALLOWS EVOLUTION OF COMPLEX ANIMALS

  • BUILD UP OF OXYGEN KILLED OFF EARLY ORGANISMS THAT COULDN'T TOLERATE IT - ALLOWED EVOLUTION OF MORE COMPLEX ORGANISMS THAT MADE USE OF OXYGEN
  • OXYGEN CREATED OZONE LAYER WHICH BLOCKED HARMFUL RAYS OF SUN - ALLOWED EVOLUTION OF EVEN MORE COMPLEX ORGANISMS
  • VIRTUALLY NO CO2 LEFT NOW

TODAYS ATMOSPHERE

  • 78% NITROGEN, 21% OXYGEN AND 0.035% CARBON DIOXIDE
  • ALSO VARIOUS AMOUNTS OF WATER VAPOUR AND NOBEL GASES (MAINLY ARGON)
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C1C - Clean Air

THE CARBON CYCLE

CARBON KEY TO GREENHOUSE EFFECT - EXISTS IN ATMOSPHERE AS CARBON DIOXIDE GAS AND IS PRESENT IN OTHER GREENHOUSE GASES

(http://www.smccd.edu/accounts/case/BIOL675_energy/img/CarbonCycle.jpg) 

  • RESPIRATION, CUMBUSTION, DECAY OF PLANTS AND ANIMALS ADD CO2 AND REMOVE O2
  • PHOTOSYTHESIS DOES THE OPPISITE
  • PROCESSES BALANCE OUT BUT HUMANS UPSET NATURAL CARBON CYCLE - AFFECTED BALANCE OF GASES 
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C1C - Clean Air

HUMAN ACTIVITY AFFECTING COMPOSITION OF AIR

  • HUMAN POPULATION INCREASING - MORE PEOPLE RESPIRING - GIVING OUT MORE CO2
  • MORE PEOPLE WITH DIFFERENT LIFESTYLES - MORE DEMAND FOR ENERGY TO SUIT IT - MORE FOSSIL FUELS BURNED - RELEASES CARBON DIOXIDE
  • MORE PEOPLE - MORE LAND NEEDED FOR HOUSING - CHOPPING DOWN TREES - CAN'T PHOTOSYNTHESISE AND REMOVE CARBON
  • LEVEL OF CARBON DIOXIDE IN ATMOSPHERE RISEN SIGNIFICANTLY IN LAST 150 YEARS

ACID RAIN

  • FOSSIL FUELS ARE BURNED AND RELEASE HARMFUL GASES LIKE SULFUR DIOXIDE AND VARIOUS NITROGEN OXIDES.
  • SULFUR DIOXIDE COMES FROM SULFUR IMPURITIES IN THE FOSSIL FUELS
  • NITROGEN OXIDES CREATED IN A REACTION BETWEEN NITROGEN AND OXYGEN IN THE AIR
  • GASES MIX WITH CLOUDS AND FORM DILUTE SULFURIC ACID AND DILUTE NITRIC ACID, WHICH THEN FALL AS ACID RAIN
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C1C - Clean Air

EFFECTS OF ACID RAIN

  • CAUSES LAKES TO BECOME ACIDIC WHICH KILLS MANY PLANTS AND ANIMALS
  • KILLS TREES, DAMAGES LIMESTONE BUILDINGS AND RUINS STONE STATUES.
  • MAKES METAL CORRODE

PHOTOCHEMICAL SMOG

TYPE OF AIR POLLUTION CAUSED BY SUNLIGHT ACTING ON OXIDES OF NITROGEN. OXIDES OF NITROGEN COMBINE WITH OXYGEN IN THE AIR TO MAKE OZONE, WHICH CAN CAUSE HEADACHES, BREATHING DIFFICULTIES AND TIREDNESS

CARBON MONOXIDE

CAN STOP BLOOD CARRYING OXYGEN AROUND BODY, LEADING TO COMAS, FAINTING AND DEATH. FORMED WHEN PETROL AND DIESEL IN CAR ENGINES BURNED WITHOUT ENOUGH OXYGEN (INCOMPLETE COMBUSTION)

CATALYTIC CONVERTER

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C1C - Clean Air

CATALYTIC CONVERTERS

  • BUILDUP OF POLLUTANTS CAN MAKE LIFE UNHEALTHY AND MISERABLE FOR HUMANS, ANIMALS AND PLANTS - NUMBER OF CASES OF RESPIRITORY ILLNESS HAS INCREASED IN RECENT YEARS
  • CATALYTIC CONVERTERS ON MOTOR VEHICLES REDUCE AMOUNT OF CARBON MONOXIDE AND NITROGEN GASES GETTING IN ATMOSPHERE - NORMALLY MADE OF PLATANIUM AND RHODIUM - HELPS UNPLEASANT EXHAUST FUMES REACT TO BE LESS IMMEDIATELY DANGEROUS
  • 2CO + 2NO -----> N2 + CO2
  • CARBON MONOXIDE + NITROGEN OXIDE -----> NITROGEN + CARBON DIOXIDE

 

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C1C - Making Polymers

WORD EQUASIONS - DISPLAYING CHEMICAL CHANGES AND REACTIONS WITH WORDS

  • EXAMPLE - METHANE BURNING IN OXYGEN TO GIVE CARBON DIOXIDE AND WATER
  • METHANE + OXYGEN -----> CARBON DIOXIDE + WATER

SYMBOL EQUASIONS - DISPLAYING CHEMICAL REACTIONS WITH SYMBOLS WHICH SHOW ATOMS IN MOLECULE

  • EXAMPLE - MAGNESIUM AND OXYGEN REACTING TO MAKE MAGNESIUM OXIDE
  • 2Mg + O2 -----> 2MgO

BALANCING SYMBOL EQUASIONS - MAKING SURE THERE ARE THE SAME NUMBER OF ATOMS ON EACH SIDE

  • EXAMPLE - H2SO4 + NaSO4 -----> Na2SO4 + H2O     BECOMES     H2SO4 + 2NaOH -----> Na2SO4 + 2H2O
  •                  2 H, 1 Na, 2 S, 8 O -----> 2Na, 1 S, 5 O, 2 H                      4 H, 1 S, 6 O, 1 Na -----> 4 H, 1 S, 6 O, 1 Na
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C1D - Making Polymers

HYDROCARBONS - COMPOUND WITH JUST HYDROGEN AND CARBON ELEMENTS (E.G. CH4, CH3(CH2)2CH3) HELD TOGETHER BY COVALENT BONDS
POLYMERS - LONG CHAIN MOLECULES FORMED WHEN LOTS OF SMALL MOLECULES CALLED MONOMERS JOIN TOGETHER - POLYMERISATION - NEEDS A CATALYST AND HIGH PRESSURE
UNSATURATED COMPOUNDS - MOLECULES WITH AT LEAST ONE DOUBLE BOND BETWEEN CARBONS
ADDITION POLYMERISATION - LOTS OF UNSATURATED MONOMER MOLECULES (ALKENES) OPEN UP THEIR DOUBLE BONDS AND JOIN TOGETHER - NAME OF MONOMER NOW HAS WORD 'POLY' IN FRONT OF IT

(http://www.chemhume.co.uk/ASCHEM/Unit%202/Ch9%20Alkanes/polymerisation_equation.jpg) 

DISPLAYED FORMULA OF MONOMER MEANS DRAWING DOUBLE BONDS BETWEEN THE CARBON AND ENCLOSING THE DISPLAY FORMULA IN BRACKETS, THEN DRAWING AN 'N' BEFORE THE BRACKETS (TO SHOW THAT THERE ARE LOTS)
DISPLAYED FORMULA OF A POLYMER MEANS DRAWING A SINGLE BOND BETWEEN THE CARBONS AND EXTENDING THE LINES ON EITHER SIDE OF THE CARBONS OUTSIDE THE BRACKETS BEFORE DRAWING AN 'N' AFTER THE BRACKETS

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C1D - Making Polymers

ALKANES - TYPE OF HYDROCARBON WITH C-C SINGLE BONDS - SATURATED COMPOUNDS

SINGLE COVALENT BONDS - TWO ATOMS SHARE ONE PAIR OF ELECTRONS

WON'T FORM POLYMERS - NO DOUBLE BONDS TO OPEN UP

(http://www.barrygray.pwp.blueyonder.co.uk/Tutoring/Tutpix/OrgChem/Alkanes.gif) 

ALL ALKANES HAVE THE FORMULA: CnH2n+2

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C1D - Making Polymers

ALKENES - HYDROCARBONS WITH DOUBLE BONDS

DOUBLE COVALENT BONDS - TWO ATOMS SHARE TWO PAIRS OF ELECTRONS INSTEAD OF ONE

CAN JOIN TOGETHER TO MAKE POLYMERS - OPEN UP THEIR DOUBLE BONDS

(http://1.bp.blogspot.com/-xx4P-LL5078/T63GShWXZqI/AAAAAAAAAS4/QWFkawMkhkg/s1600/cracking-alkenes-491.gif)  (ALL END IN 'ENE)'

ALL ALKENES HAVE THE FORMULA: CnH2n

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C1D - Making Polymers

BROMINE WATER TEST - TESTS WHETHER HYDROCARBON IS ALKANE OR ALKENE

  • BROMINE WATER - BRIGHT ORANGE SOLUTION CONTAINING BROMINE - VERY REACTIVE - REACTS WITH DOUBLE BONDS
  • IF YOU ADD A SATURATED COMPOUND (LIKE AN ALKANE), WATER WILL STAY BRIGHT ORANGE
  • IF YOU ADD AN ALKENE, AN ADDITION REACTION WILL TAKE PLACE - BROMINE WILL ADD TO DOUBLE BOND AND THE WATER WILL BE DECOLOURISED, MAKING A COLOURLESS DIBROMO COMPOUND
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C1E - Designer Polymers

POLYMER PROPERTIES AND USES

  • STRONG, RIGID - (E.G. HIGH DENSITY POLYETHENE) - PLASTIC MILK BOTTLES
  • LIGHT, STRETCHABLE - (E.G. LOW DENSITY POLYETHENE) - PLASTIC BAGS AND SQUEEZY BOTTLES - LOW MELTING POINT - NOT GOOD FOR ANYTHING HOT
  • PVC - STRONG, DURABLE, CAN BE MADE EITHER RIGID OR STRETCHY - RIGID KIND USED FOR WINDOW FRAMES AND PIPING - STRETCHY KIND USED FOR SYTHETIC LEATHER
  • POLYSTYRENE FOAM - USED IN PAKAGING TO PROTECT BREAKABLE THINGS - USED FOR COFFEE CUPS (GOOD THERMAL INSULATOR)

MAKING CLOTHES

  • NYLON - SYNTHETIC POLYMER THAT CAN BE COATED WITH POLYURETHANE TO MAKE TOUGH, HARD-WEARING, WATERPROOF OUTDOOR CLOTHING THAT KEEPS UV LIGHT OUT
  • PROBLEM - POLYURETHANE COATING DOESN'T LET WATER VAPOUR PASS THROUGH IT - SWEAT CONDENSES ON THE INSIDE, MAKING SKIN AND CLOTHES GET WET OR UNCOMFORTABLE
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C1E - Designer Polymers

GORE-TEX FABRICS

HAVE ALL THE USEFUL PROPERTIES OF NYLON/POLYURETHINE PRODUCTS BUT ARE ALSO BREATHABLE - ALLOWS SOMEONE TO STAY DRY IN THE RAIN WITHOUT GETTING SOAKED IN SWEAT
MADE BY LAMINATING A THIN FILM OF PLASTIC (CALLED EXPANDED PTFE) ONTO A LAYER OF ANOTHER FABRIC (LIKE POLYESTER OR NYLON) - MAKES THE PTFE STURDIER
PTFE FILM HAS TINY HOLES WHICH LET WATER VAPOUR THROUGH - BREATHABLE BUT ALSO WATERPROOF - HOLES AREN'T BIG ENOUGH TO LET BIG WATER DROPLETS THROUGH AND PTFE FILM REPELS LIQUID WATER

NON-BIODEGRADABLE PLASTICS

MOST POLYMERS AREN'T BIODEGRADABLE - NOT BROKEN DOWN BY MICROORGANISMS SO DON'T ROT - DIFFICULT TO GET RID OF
BURYING IN LANDFILL SITES - STILL BE THERE IN YEARS TO COME - WASTE OF LAND AND PLASTIC
BURING PLASTICS - RELEASES GASES LIKE ACIDIC SULFUR DIOXIDE AND POISENOUS HYDROGEN CHLORIDE AND HYDROGEN CYANIDE
REUSE PLASTICS AND THEN RECYCLE - SORTING OUT DIFFERENT PLASTICS DIFFICULT,  EXPENSIVE - CHEMISTS WORKING ON MAKING BIODEGRADABLE POLYMERS - BREAK DOWN/DISSOLVE - AVOID DISPOSAL PROBLEMS

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C1E - Designer Polymers

INTERMOLECULAR FORCES IN PLASTICS

WEAK FORCES

CHAINS HELD TOGETHER BY WEAK INTERMOLECULAR FORCES - CHAINS FREE TO SLIDE OVER EACHOTHER - PLASTIC WILL BE STRETCHED EASILY AND HAVE A LOW MELTING POINT

(http://1.bp.blogspot.com/-eOnQ-4iPxBU/UZ_ZWPmMsJI/AAAAAAAAJA8/JAgFqGqViug/s1600/b13blog+wavy+line+landscape.jpg) 

STRONG FORCES

STRONGER BONDS BETWEEN CHAINS - COVELANT BONDS BETWEEN CHAINS OR CROSS LINKING BRIDGES - CROSS LINKS HOLD CHAINS FIRMLY TOGETHER - HIGHER MELTING POINT, CAN'T BE STRETCHED, RIGID

(http://soft-matter.seas.harvard.edu/images/thumb/e/ef/Cross-link1.png/500px-Cross-link1.png)

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C1F - Cooking and Food Additives

WHY FOODS ARE COOKED

  • BETTER TASTE AND TEXTURE
  • SOME FOODS EASIER TO DIGEST WHEN COOKED
  • HIGH TEMPERATURES KILL OFF MICROBES THAT CAUSE DISEASE
  • SOME FOODS ARE POISONOUS WHEN RAW

CHEMICAL CHANGES

COOKING CAUSES CHEMICAL CHANGES - IRREVERSABLE PROCESS

EGGS AND MEAT - SOURCES OF PROTEIN - PROTEIN MOLECULES CHANGE SHAPE WHEN HEATED - ENERGY FROM COOKING BREAKS SOME OF THE CHEMICAL BONDS IN PROTEIN - ALLOWS MOLECULE TO TAKE DIFFERENT SHAPE - MAKES FOOD A MORE EDIBLE TEXTURE - DENATURING

POTATOES - PLANTS - EACH POTATO CELL SURROUNDED BY RIGID CELL WALL MADE OUT OF CELLULOSE - HUMANS CAN'T DIGEST CELLULOSE - CAN'T GET TO NUTRIENTS INSIDE CELL - COOKING RUPTURES CELL WALL AND MAKES STARCH GRAINS SWELL UP AND SPREAD OUT - SOFTER, MORE FLEXIBLE, EASIER TO DIGEST

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C1F - Cooking and Food Additives

BAKING POWDER

  • BAKING POWDER HEATED - UNDERGOES THERMAL DECOMPOSITION
  • SODIUM HYDROCARBONATE -----> SODIUM CARBONATE + CARBON DIOXIDE + WATER
  • 2NaHCO3 -----> Na2CO3 + CO2 + H2O
  • USED IN BAKING CAKES - CARBON DIOXIDE PRODUCED MAKES CAKES RISE

TEST FOR CARBON DIOXIDE - BUBBLE THROUGH LIME WATER - TURNS CLOUDY IF CO2 PRESENT

FOOD ADDITIVES 

  • FOOD COLOURS - MAKES FOOD LOOK MORE APPETISING
  • FLAVOUR ENHANCERS - BRING OUT TASTE AND SMELL OF FOOD WITHOUT ADDED TASTE OF THEIR OWN
  • ANTIOXIDENTS - HELP PRESERVE FOOD
  • EMULSIFIERS - HELP OIL AND WATER BLEND TOGETHER
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C1F - Cooking and Food Additives

EMULSIFIERS

  • EMULSION - OIL AND WATER MIXED TOGETHER - MADE UP OF LOTS OF ONE LIQUID SUSPENDED IN ANOTHER LIQUID
  • OIL AND WATER NATURALLY SEPERATE INTO TWO LAYERS (OIL ON TOP OF WATER) - EMULSIFIERS STOP THEM FROM SEPERATING OUT
  • TWO ENDS - HYDROPHILIC (ATTRACTED TO WATER) AND HYDROPHOBIC (ATTRACTED TO OIL) - HYDROPILIC BONDS TO WATER AND HYDROPHOBIC BONDS TO OIL, CAUSING THE OIL TO FORM DROPLETS SURROUNDED BY A COATING OF EMULSIFIER - HYROPHILIC BIT FACING OUTWARDS - OIL DROPLETS REPELED BY HYDROPHILIC ENDS WHILE WATER MOLECULES BIND ON - WON'T SEPERATE
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C1G - Smells

ESTERS

  • NATURAL ESTERS - FROM NAUTURE E.G. FRUITY SMELLS LIKE APPLES
  • ARTIFICIAL ESTERS - MANUFACTURED SYNTHETICALLY TO USE AS PERFUMES OR FLAVOURINGS

ESTIFICATION - PRODUCTION OF ESTERS

  • ACID + ALCOHOL -----> ESTER + WATER
  • METHOD - MIX 10CM3 OF CARBOXYLIC ACID WITH EQUAL AMOUNT OF ALCOHOL - ADD 1CM3 OF CONCERNTRATED SULPHURIC ACID AND WARM GENTLY FOR 5 MINUTES - TIP MIXTURE INTO 150CM3 SODIUM CARBONATE SOLUTION TO NEUTRILISE ACIDS

PROPERTIES NEEDED IN PERFUMES

  • EASILY EVAPORATES - SO IT IS ABLE TO BE SMELLED
  • NON - TOXIC - SO IT DOESN'T SEEP THROUGH SKIN AND POISON PERSON
  • DOESN'T REACT WITH WATER OR IRRITATE SKIN - SO IT DOESN'T REACT WITH SWEAT OR BURN SKIN
  • INSOLUBLE IN WATER - DOESN'T WASH OFF WHEN PERSON GETS WET
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C1G - Smells

TESTING NEW PERFUMES

  • PRODUCTS NEEDED TO BE TESTED THOUROUGHLY BEFORE RELEASE TO PUBLIC TO MAKE SURE THEY'RE SAFE TO USE
  • SOME TESTS CARRIED OUT USING ANIMALS - CONTROVERSIAL - SOME THINK IT'S WORTH IT TO CHECK PRODUCTS WON'T DAMAGE HUMANS - SOME CLAIM THAT IT'S WRONG TO CAUSE SUFFERING TO ANIMALS WHEN THE PRODUCT ISN'T A NECESSITY FOR HUMANS, ESPECIALLY IF RESULTS NOT CONCLUSIVE
  • TESTING COSMETICS ON ANIMALS - BANNED IN EU - CONCERNS ABOUT ANIMAL WELFARE

SOLUTIONS - MIXTURE OF SOLVENT AND SOLUTE THAT DOES NOT SEPARATE OUT

  • SOLUTE - SOLID SUBSTANCE BEING DISSOLVED
  • SOLVENT - LIQUID IT'S DISSOLVING INTO
  • SOLUBLE - SOLID THAT WILL DISSOLVE IN SOLVENT
  • INSOLUBLE - SOLID THAT WILL NOT DISSOLVE IN SOLVENT
  • SOLUBILITY - MEASURE OF HOW MUCH IT WILL DISSOLVE
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C1G - Smells

NAIL VARNISH

  • NOT SOLUBLE IN WATER - FORCES BETWEEN PARTICLES IN WATER MOLECULES AND FORCES BETWEEN PARTICLES IN NAIL VARNISH MOLECULES ARE STRONGER THAN FORCES BETWEEN NAIL VARNISH AND WATER MOLECULES - PARTICLES MORE ATTRACTED TO THEMSELVES THAN EACHOTHER
  • SOLUBLE IN ACETONE - ATTRACTION BETWEEN NAIL VARNISH MOLECULES AND ACETONE MOLECULES STRONGER THAN FORCES HOLDING INDIVIDUAL PARTICLES TOGETHER - USED AS NAIL POLISH REMOVER

SOLVENTS

  • EVALUATE BEST SOLVENT TO USE, TAKING INTO ACCOUNT PROPERTIES LIKE SOLUBILITY, BOILING POINT AND SAFETY
  • E.G. A SUBSTANCE THAT IS RELATIVELY SOLUBLE AND IS NON TOXIC WOULD BE THE BEST SOLVENT TO USE
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C1H - Paints and Pigments

PAINTS

  • MADE UP OF SOLVENT, BINDING MEDIUM AND PIGMENT
  • PIGMENT - GIVES PAINT IT'S COLOUR
  • BINDING MEDIUM - LIQUID THAT CARRIES PIGMENT BITS AND HOLDS THEM TOGETHER - STICKS PIGMENTS TO PAINTED SURFACE WHEN TURNS SOLID
  • SOLVENT - THINS PAINT AND MAKES IT EASIER TO SPREAD

COLLOIDS

  • TINY PARTICLES OF A SUBSTANCE DISPERSED (NOT DISSOLVED) THROUGH ANOTHER SUBSTANCE
  • DON'T SPERATE OUT BECAUSE PARTICLES ARE SO SMALL - DON'T SINK TO BOTTOM
  • PAINT - COLLOID WHERE PARTICLES OF PIGMENT (SOLID) ARE DISPERSED THROUGH A LIQUID
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C1H - Paints and Pigments

EMULSION PAINTS - WATER BASED

  • SOLVENT USED IS WATER - BONDING MEDIUM USUALLY ACRYLIC OR ACCETATE POLYMER
  • DRIES WHEN SOLVENT EVAPORATE - LEAVES BINDING MEDIUM AND PIGMENT AS THIN SOLID FILM - THIN LAYER OF EMULSION PAINT DRIES QUITE QUICKLY
  • FAST DRYING - DON'T GIVE OFF HARMFUL FUMES - PERFECT FOR PAINTING INSIDE WALLS

GLOSS PAINTS - OIL BASED

  • BINDING MEDIUM IS OIL - SOLVENT IS ORGANIC COMPOUND THAT WILL DISOLVE OIL
  • DRIES IN TWO STAGES - OIL EVAPORATES THEN OIL IS OXIDISED BY OXYGEN IN AIR BEFORE TURNING SOLID - TAKE LONGER TO DRY THAN WATER BASED PAINTS
  • GLOSSY, WATERPROOF, HARD-WEARING - SOMETIMES GIVE OFF HARMFUL FUMES - BEST FOR PAINTING OUTSIDE WALLS, DOORS AND METAL WORK
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C1H - Paints and Pigments

  • THERMOCHROMIC PIGMENTS - CHANGE COLOUR OR BECOME TRANSPARENT WHEN HEATED OR COOLED
  • DIFFERENT PIGMENTS CHANGE COLOUR AT DIFFERENT TEMPERATURE - USED TO MAKE COLOUR CODED TEMPERATURE SCALE - BASIC THERMOMETERS
  • USED IN ELECTRIC KETTLES THAT CHANGE COLOUR AS BOILED
  • BABY PRODUCTS - BATH TOYS AND BABY SPOONS - SAFETY FEATURE - CAN TELL IF TOO HOT
  • MOOD RINGS - CHANGE COLOUR DEPENDING ON TEMPERATURE OF FINGER
  • CAN BE MIXED WITH ACRYLIC PAINT TO GIVE WHOLE RANGE OF COLOUR CHANGES E.G. MIXING BLUE PIGMENT THAT LOSES COLOUR OVER 27 DEGREES WITH YELLOW PAINT GIVES PAINT THAT IS GREEN BELOW 27 DEGREES
  • ALSO USED ON NOVELTY MUGS - DESIGN THAT CHANGES COLOUR WHEN HOT DRINK POURED INTO THEM - SOME GO TRANSPARENT WHEN HOT DRINK POURED
  • PHOSPHORESCENT PIGMENTS - ABSORB NATURAL OR ARTIFICIAL LIGHT AND STORE ENERGY IN THEIR MOLECULES - RELEASE OVER TIME - GLOW IN THE DARK
  • USED FOR WATCHES WITH GLOW IN THE DARK HANDS, NOVELTY DECORATIONS, EXIT SIGNS 
  • WATCHES USED TO USE RADIOACTIVE PAINTS - WOULD GLOW IN DARK FOR YEARS WITHOUT NEEDING TO BE PUT IN LIGHT TO CHARGE UP - NOT SAFE - GAVE OFF ATOMIC RADIATION
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