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  • Created by: Giggles
  • Created on: 10-05-17 17:27

atoms, molecules and compounds

Atoms can form bonds to make molecules or compunds.

displayed and molecular formulas

molecular formula - show the number and type of atoms in a molecule

displayed formula - it show the atoms and the cobalent bonds in a molecule as a picture.

methane contain 1 carbon atom and 4 hydrogen atoms. CH4  (molecular formula)

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emulsifiers

addictives: 

  • food colours - make food look more appealing                                                                    
  • flavour enhancers - bring out taste and smell of food without adding taste
  • antioxidants - help to preserve food
  • emulsifiers help oil and water mix
  • emulsifiers are molecules with one part that attracted to water and another part attracted to oil
  • hydrophilic = attracted to water,  hydrophobic = attracted to oil
  • hydrophilic end of each emulsifier molecule bond to water molecules and hydrophobic moleecule bond with oil molecules.
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cooking and chemical change

why cook

  • better taste and texture
  • easier to digest
  • high temperature kill off microbes that cause disease 
  • some foods are poisonous when raw and must be cooked to be edible

cooking causes chemical changes

  • protein molecules change shape when heated
  • energy fro cooking break chemical bonds
  • irreversable
  • potatoes - cooking break down the cell walls - make the patatoe softer easier to digest

baking powder

  • baking cakes - carbon dioxide produce make the cake rise
  • limewater detect carbon dixoxide - turns cloudy
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perfumes

  • natural source: fruits and flowers
  • artificial source: esters

equation:  acid + alcohol - ester + water

properties

  • easily evaporates - wont reach nose and be able to be smelt
  • non toxic - mustnt seep through skin and poison you
  • doesnt react with water - react with sweat
  • doesnt irrartate the skin - couldnt apply directly
  • insoluble in water - if soluble in water it would wash off

testing  - check to find out if it damage humans

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solutions

solution - mixture of a solute and a solvent that does not separate out

solute - the substance being dissolved

solvent  - the liquid it dissolving in

soluble - it will dissolve

insoluble - it will not dissolve

solubility - measure of how much will dissolve

learn the definitions

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solutions

nail varnish is insoluble in water

  • molecules of nail varnish are strongly attracted to each other
  • attraction stronger than attraction between the nail varnish and water molecules
  • molecule of water are strongly attracted to each other
  • this attraction is stronger than the attraction between the water molcules and the nail varnish molecules

nail varnish dissolve in acetone

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paints and pigments

  • pigment - give the paint it colour
  • binding medium - liquid that carries pigments. when it goes solid it sticks the pigments to the surface.
  • solvents - thins the paint and make it spread out easier

paint is a collide where particles of a pigment are disperesed through a liquid

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special pigments

  • thermochromic pigments - change colour when heated
  • different pigment change at different temperatures
  • baby products
  • bath toys
  • baby spoon
  • phosphorescent pigments
  • absorbe natural or artificial lighting and store the energy. energy realeased as light over time
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polymers

  • ploymers are formed when lots of small molecules called monmers join together
  • this reaction is called polymerisation
  • molecules with at least dobule covelent bond between carbon atoms are called unsatutrated
  • molecule with no covelent bond between carbon atoms are called saturated

force between molecule determine the properties of plastics

weak force: if the plastic is made up of long chanins that are held together by weak intermolecular forces, then the chains will be free slide over each other. this means that the plastic can stretched easily, and will have a low meting point.

stong forces: some plastic have stonger bonds between the polymer chains- these might be covelent bonds between the chains  or cross linking bridges . these plastics have high melting point, are rigid and cant be streached, as the crosslink hold holdthe chains firmly together

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polymers and their uses

  • strong polymers are used to make plastic milk bottle
  • light polymer used for plastic bags and squeezy bottles.
  • pvc this is used to make window frame and piping . this is also used to make synthetic leather
  • polystyrene foam is used in packaging to protect breakable things, and it used to make disposable cofffee cups.
  • nylon is a synthetic polymer used to make clothing. but is coated with polyurethane
  • this doesnt let water vapour pass through it.
  • gore tex have useful properties of these but are also breathable
  • gore tex are made by a thin film of plastics called expanded ptfe onto nylon/polyuurethane
  • ptfe has tiny holes which let water vapour through so it breathable. but its waterproof, the holes arent big enough to let big water droplets through and ptre repels liquid water
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hydrocarbons

hydrocarbon ONLY contain hydrogen and carbon atoms

alkane have all c-c single bonds

alkanes are types of hydrocarbon

alkanes wont form polymers, no double bonds

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hydrocarbon - alkenes

alkenes have a c=c double bond

their double bonds ca open up and join onto things.

examples include: ethene, propene, butene

alkenes reat with bromine water

when bromine water + alkane no reation will happen and the colour will remain bright orange

bromine water + an alkene  reaction will happen, bromine will add to the double bond making a colourless compound. the bromine water is discoloured.

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fractional distillation of crude oil

  • fraction order from bottom up: bitumen, oil, diesel, paraffin, naphthna, petrol, lpg (liquefied petroleum gas)
  • crude oil is a mixture of hydrocarbons
  • crude oil is seperated by fractional distillation. oil is heated unitl most of it is gas.
  • its hot at the bottom and gradually gert cooler at the top
  • longer hydrocarbons have high melting point. they turn into liquis and drain out of the column early on, near the bottom.
  • shorter hydrocarbons have lower melting point. they turn liquid and drain out much later on , near the top of the column.
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cracking

  • cracking is splitting up long chain hydrocarbon
  • longer molecule produced from fractional distillation are cracked into smaller one because there are more demand for products - petrol and kerosene 

condition needed for cracking

  • catalyst at 400 - 700 oc ( high temp and catalyst)
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use of fossil fuels

  • crude oil provide enrgy for - generating electricity, heating homes
  • oil - cars, planes, trains
  • crude oil is non renewable

oil can cause polictical and environmental problems

political  -

  • oil get used up, price will increase. countires will keep oil and wont sell it
  • countries with most oil and natural gas will have power over other countries - supply or not
  • countries without will depend on politically unstable countries for supplies.

environmental -

  • oil being realeased to sea caused by oil tanker crashes.
  • oil covers birds feathers and stop them from being waterproof
  • detergent can harm wildlife.
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more on uses of fossil fuels

chossing the best fuels

T - toxicity

E - energy value

A - availability

C - cost

U - use easiliy

P - pollution

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evolution of the atmosphere

volcanoes  gave out steam and CO2

green plants evolved and produced oxygen

ozone layer allows evolution of complex animals

today atmospher -

  • nitrogen - 78%
  • oxygen - 21%
  • carbon monoxide - 0.035%
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the carbon cycle

  • carbon is constantly being recycled
  • in the atmosphere it exist as carbon dioxide gas

carbon move in a cycle

  • respiration, combusion and decay of plants and animals add carbon dioxide to the air and add oxygen
  • photosynthesis does the opposite - it removes carbon dioxide and adds oxygen
  • these processess should all balance out. humans have disturbed the natural carbon cyle which has affected the balannce of gases in the stmosphere
  • human population is increasing meaning more people are respiring giving out more carbon dixoxide
  • more people mean more energy. demand is increasing  - increase energy consumption come from burning fossil fuel whic realease carbon dioxide
  • more land is needed to bulid land and food.
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air pollution and acid rain

acid rain is caused by oxides of nitrogen

nitogen oxide mix with clouds and form dilute nitric acid - acid rain formed

acid rain kill plants and animals - becom acidic

carbon monoxide is a poisonous gas

can stop the blood from carrying oxygen around the body

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