Organic chemistry combined chem notes

Chapter 15: Fuels and Crude Oil 15.1 - Importance of natural gas and crude oil in our lives Methane and crude oil are non-renewable sources of energy 15.2 - Separation of crude oil/petroleum Crude oil Crude oil contains a mixture of hydrocarbons Hydrocarbons are compounds containing carbon and hydrogen only Separation of crude oil Name (in order of fractions) No. of carbon atoms Boiling point/ °C Uses Liquefied petroleum gas (LPG) 1-4 40< Fuel for cooking Petrol (gasoline) 5-10 40-75 Fuel in cars Naphtha 7-14 75-150 Feedstock for the petrochemical industry Kerosene (paraffin) 11-16 160-250 Fuel for heating and cooking Fuel for aircraft engines Diesel 16-20 250-300 Fuel for diesel engine Lubricating oils 20-50 300-350 Lubricants For polishes and waxes Bitumen >50 >350 Making road surfaces Mnemonic Love Pushing Naughty Kids Down Oversized Bags Process of separation Fractional distillation: - Crude oil is heated and turns into vapour, then enters the fractionating column - As hot vapour rises up the column, it cools and condenses at different temperatures - The fractions with the lowest boiling point condense at the top , then removed - The fractions with the highest boiling points condense at the bottom

15.3 - Changes in properties for different fractions As the size and mass of the hydrocarbons increase down the fractions from LPG to Bitumen : Boiling point increase When the size of molecules increases, intermolecular forces of attraction increase, and more energy is needed to overcome these forces Viscosity increase When the size of molecules increases, intermolecular forces of attraction increase, the forces are harder to overcome, and the larger hydrocarbons do not flow easily Flammability decreases When the size of the hydrocarbon increases, the percentage of mass of hydrogen in the molecule decreases, and hydrogen is flammable Competing uses of crude oil - It is non-renewable - To meet the competing uses of crude oil, there is a growing need for its conservation - Thus, use alternatives like solar energy, biofuels Biofuels Bioethanol is obtained by fermentation of sugar in sugarcane to ethanol (seen in 17.1) Ethanol + Oxygen → CO 2 + Water Better for the environment because it offsets the carbon dioxide emission during burning by absorbing carbon dioxide during plant growth Chapter 16/17: Alkanes and Alkenes, Alcohols and Carboxylic Acids 16.1 - Organic chemistry Organic compounds are a class of chemical compounds in which one or more atoms are covalently bonded to atoms of other