Finite resurce of natural fuels like coal and gas formed by the remains of living orgaisms
Hydrocarbons in different fractions have different boiling points. The forces between the molecules are intermolecular forces and are broken during boiling. The molecules of the liquid separate as molecula of a gas. Large molecules such as those of bitumen and heavy oil have strong forces of attraction. A lot of energy is needed to break the forces between the molecules. These fractions have high boiling points. Smaller molecules such as petrol have weak attractive forces between them and are easily separated. Less energy is needed to break the forces between the molecules. These fractions have low boiling points.
There may be political problems related to the extraction of crude oil. The UK is dependent on politically unstable countries. Oil producing nations can set high prices and cause problems for the future supply of non-oil producing nations.
Because th demand for oil and its products is very high, there is conflict between the needs for making petrochemicals and for making fuels. Naptha is in high demand for usse in medicines, plastics and dyes.
Oil slicks can damage birds' feathers and cause their deaths. Clean-up operations use detergents that can damage wildlife.
Cracking is a process that turns large alkane molecules into smaller alkane and alkene molecules.
For example C8 H18 --> C2 H4 + C6 H14
Ease of use
Complete combustion: fuel + oxygen --> carbon dioxide + water (+energy)
Incomplete combustion: fuel + oxygen(not plenty) --> carbon/carbon monoxide + water
Emulsifiers stop two liquids from s .
An emulsifier molecule has a hydrophilic head and a hydrophobic t
The head bonds with water molecules and the tail bonds with the o molecules.
Mayonnaise, low fat spread and ice cream contain e .
Many foods have a better taste and t when cooked.
Some foods are easier to d when they are c.
High temperatures kill off m .
Some foods are poisonous when they are r .
Protein molecules change shape when you h them.
The energy from cooking breaks some of the chemical bonds in the p and this allows the molecule to take a different shape.
This gives the food a more edible t .
The change is irreversible and is called d .
Cooking the potato ruptures the c___ w____.
It also makes the s_____ grains swell up and spread out.
These changes make the potato s_____ and more flexible and much more easier to d_____.
Sodium h________________--> sodium _________+carbon dioxide +water
Acid + Alcohol --> Ester + water (concentrated sulphuric acid is used as a catalyst)
Insoluble in water
Doesn't react with water
Doesn't irritate the skin
选择要在Apple App Store上查看的Topgrade应用程序。