C1b oils earth and atmosphere
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C1b Oils, Earth and Atmosphere. Oils from Plants. Solar powered. Plants use energy from the sun: energy from sun 6CO 2 + 6H 2 0 C 6 H 12 0 6 + 6O 2 Plants turn glucose into other chemicals Can be useful to us. Rapeseed – vegetable oil Collect seeds after plant has flowered

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C1b Oils, Earth and Atmosphere

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C1b oils earth and atmosphere

C1b Oils, Earth and Atmosphere

Oils from Plants


Solar powered

Solar powered

  • Plants use energy from the sun:

    energy from sun

    6CO2 + 6H20 C6H1206 + 6O2

  • Plants turn glucose into other chemicals

  • Can be useful to us


Vegetable oils

Rapeseed – vegetable oil

Collect seeds after plant has flowered

Crushed, pressed to extract oil

Impurities removed

Important food stuff

Extraction using steam

Lavender oil - distillation

Plants boiled in water

Steam contains oil

Collected, water and impurities removed

Vegetable oils


Oils as foods

Oils as foods

  • Contain loads of energy

  • Hydrocarbon molecules

  • May be saturated or unsaturated

  • Tested with bromine water


Cooking with veg oils boiling point

Cooking with veg oils: Boiling point

  • Temperature depends on forces between molecules

    • Bigger force = higher boiling temperature

  • Molecules in veg. oils are much larger than water molecules

    • Bigger forces

    • Higher boiling point

  • Higher temperatures = different reactions

  • Food cooks differently


Soak it up

Increases the energy content of the food

Needs to be used

Why can too much fried food be bad for you?

Food absorbs some of the oil it’s cooked in

Veg oils very high in energy

Soak it up


Hydrogenated oils

Hydrogenated oils

  • Unsaturated oils are liquid at RToC

    • Double bond stops molecules fitting together well

    • Reduces the forces between molecules

  • Boiling point can be increased

  • Adding hydrogen, replacing double bonds

    • Molecules fit together better

    • Increased forces = higher boiling point


Hydrogenated oils1

Hydrogenated oils

  • Higher melting point – solid at RToC

  • “Hardening” of vegetable oils

  • Hydrogenated oils

  • Can be used to make spreads, margarine etc.


Smooth operator

Smooth operator

  • Texture of food is very important

    • Ice cream, mayonnaise etc.

  • Mixture of oil and water – don’t mix!

  • Can be persuaded

    • Very small droplets of oil

    • Spread throughout water

    • Emulsion

  • Milk is an everyday example


Emulsifiers

Emulsifiers

  • Encourages oil and water to stay mixed

  • Egg yolk in mayonnaise

  • Gives a thick texture


Emulsion paint

Emulsion paint

  • Emulsion paint is NOT an emulsion!

  • It is a powder suspended in a liquid

    • Colloid


Preservation

Preservation

  • Need to make food last longer – preserve it

    • Salt (remove water)

    • Vinegar (pickling)

    • Alcohol (kill microbes)

  • Knowledge of chemistry

  • Also use chemistry to improve flavours or appearance


Food additives

Food additives

  • Substance added to a food

    • Food additive

  • Approved for use in Europe

    • Given an ‘E’ number

    • Identify them rather than name them

  • Eg.E102 is tartrazine (yellow colouring)

    E220 is sulphur dioxide (preservative)

  • Six types of additive


Food additives1

Food additives


Detecting additives

Detecting additives

  • Food scientists – investigate what has been added

  • Complicated versions of simple techniques

  • Chromatography

    • How well something dissolves in a solvent

    • Solubility determines how far they move across a surface

    • Separation technique


Fuels from plants

Fuels from plants

  • Biodiesel - Name given to fuel made from vegetable oil

  • Oil is treated to remove unwanted chemicals

    • Used on its own

    • Mixed with diesel refined from crude oil

  • Other by-products:

    • Solid material = high energy cattle feed

    • Glycerine = used in soap


Benefits and advantages

Biodiesel gives off carbon dioxide when burnt

Biodiesel is grown

Crops used absorb carbon dioxide as they grow

C02 produced is absorbed by plants

Carbon neutral

No greenhouse gases

Very clean in terms of pollution

Very little sulphur dioxide

Not harmful to animal and plant life

If spilled, breaks down much faster than ‘normal’ diesel

Benefits and advantages


Other bio fuels

Other bio-fuels

  • Ethanol (alcohol)

    • Fermenting sugar from sugar cane

    • Used in Brazil a lot – added to normal petrol

  • Gives off CO2 when burnt

    • Absorbed by plants during photosynthesis

  • Ethanol can also be made from ethene

    C2H4 + H20  C2H5OH

  • Not carbon neutral


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