Chemistry alkanes

• Fractional distillation

  Large me have a higher boiling point

  so condense at the bottom as it is cooler at the bottom, smaller molecules have a lower boiling point and evaporate at the top
• Cracking- large hydrocarbons are broken into smaller hydrocarbons
• Cracking is used because smaller molecules are in higher demand and are more valuable
• Thermal cracking uses high pressure, high temp and produces mostly alkenes
• Catalyctic cracking uses high temp and lower pressure the catalyst is a zeolite and it produces branched and cyclic alkanes and aromatic hydrocarbons and is used to make motor fuels
• Sulfur dioxide can be removed from flue gases by neutralising it with calcium oxide
• The removal of sulfur dioxide may not by 100% efficient because of incomplete combustion
• Platinum is a catalyic converter
• The catalytic converter has a honey comb structure to increase surface area so reaction is faster
• A thin layer of catalyst is used as only a small amount of metal is needed so it has a bigger SA:V
• Alkanes are saturated hydrocarbons
• all carbon atom has four covalent bonds and each hydrogen has one
• Bond angle in an alkane is 109.5 except in a cycle alkane, where is smaller
• almost alkanea are nonpolar because the electronegativity difference between carbon and hydrogen is similar so they have VanderWaal forces
• alkanes have a low boiling point so smaller alkanes are gases at room temperature. However it does increase as the molecules get bigger so large alkanes are liquid and very large. alkanes are solid at room temperature
• Alkanes that have branches have a lower boiling points than unbranched alkanes and this is because the intermolecular forces are weaker due to the surface area of tension being bad so the Vander war forces are weaker
• alkanes are insoluble and water, because it is nonpolar and water is polar and only polar solvent can dissolve polar substances
• Are unreactive because the carbons to carbon bonds are strong and the carbons to hydrogen bonds are strong
• Are flammable because they make fuels lubricants and used to make smaller molecules
• Fractional distillation is a physical process as no bonds are broken. It is hotter at the bottom and cooler at the top.
• A furnace is at the bottom of the fraction column, and that heats the oil up into gas
• Shorter our canes rise further up the column as they have a lower boiling point, so I have to get cooler to condense
• The longer chains stay near the bottom of the column as they have higher boiling points, so they need to be heated more to turn them back into gases
• Shorter alkanes have a lower boiling points are more volatile and more flammable and less viscous
• Alkanes all cracked into smaller, alkanes as they are higher in demand
• Thermal, cracking, a high temperature of 1000 K and a high-pressure of 7000 KPA is needed
• In thermal, cracking the carbon to, carbon bond brakes and one pair of the electron goes to each carbon and this makes a free radical which are very reactive
• In thermal, cracking can produced alkenes and hydrogen
• Catalytic cracking uses high temperature lower pressure and a catalyst is used which is zeolite and it has a honeycomb structure which means a small amount of catalyst is used for larger surface area which lows the cost
• Catalytic cracking, produces branched, alkanes, cyclo, alkanes, and aromatic compounds, e.g. benzene
• In catalytic, cracking, a small amount of a hydrocarbon and a catalyst is placed in a tube and the catalyst is heated, and then the alkane then moves across the catalyst where gets broken and moves down the delivery tube and rises up through the water in bubbles and a displaces, the water, which moves down
• fuel is something that releases energy as it burns
• carbon monoxide is a poisonous gas
• Carbon particles, a.k.a. soot can make asthma worse and can cause skin cancer
• carbon dioxide and water vapour are greenhouse gases
• Sulphur dioxide makes acid rain and nitrogen oxide can react with water to make acid rain
• Unburnt hydrocarbons can react with nitrogen oxide to make a photochemical mug, which can interfere with sunlight and have a haze effect
• The honeycomb structure of the catalytic converters, maximise collisions between the gases and the catalyst
• Platinum, radium and rhodium are used as catalytic converters
• Polluting gases reacts with each other, when passing through the catalytic converter to make less pollutants substances