Chapter 14

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Alkane: This is the most basic organic compound and usually consists of only C–C bonds and C–H bonds. Alkene: This indicates that there is a C=C (carbon to carbon) double bond present. Alcohol: This indicates that there is an O–H group present. Carboxylic acid: This shows there is a carbon which has a C=O double bond with oxygen, and a single bond to an OH group. meth- contains one carbon atom eth- contains two carbon atoms prop- contains three carbon atoms but- contains four carbon atoms pent- contains five carbon atoms.

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coal, natural gas and petroleum

methane

a mixture of hydrocarbons and its separation into useful fractions by fractional distillation

The less carbon atoms, the lower the boiling point. As the number of carbon atoms in the hydrocarbon increases: - the boiling point increases - the viscosity increases - the volatility decreases.

Refinery gas: used as bottled gas for heating and cooking. Gasoline: used as a fuel for cars. Naphtha: used as a base for manufacturing many other chemicals, for example, solvents used by painter decorators. Kerosene: used for jet fuel Diesel oil: used as a fuel for trucks in diesel engines. Fuel oil: used as a fuel for ships or heating homes. Lubricating oil: used for lubricating machinery, and as a base for polishes and waxes. Bitumen: used for laying tarmac on roads.

a ‘family’ of similar compounds with similar chemical properties due to the presence of the same functional group

They have the same structural formula; all come from the same functional group; similar chemical properties. the alkanes as a homologous series are generally unreactive except for combustion reactions. The alkenes that have a C=C bond are similar to alkanes except that they are more reactive due to the double bond that can break and open up to join with other atoms. The alcohols that contain the –OH functional group display the property of miscibility in water, whereas alkanes without the –OH group are not miscible in water. Carboxylic acids with the –COOH readily undergo further chemical reactions and so, for example, can react with alcohols to form esters as we discovered in previous subtopics. The share the similar chemical properties and the same functional groups

when compounds have similar molecular formulas but different arrangement of atoms

generally unreactive, except in terms of burning

Alkanes are generally unreactive due to the strength of their covalent bonds. They are often referred to as saturated hydrocarbons. This means that the molecule only has single covalent bonds. They contain only C-C bonds and C-H bonds and each carbon forms 4 covalent bonds.

In a substitution reaction, an alkane reacts with a halogen to produce a halogenoalkane. This reaction is photochemical, only reacting in the presence of sunlight. Chlorine molecules (Cl 2 ) are split up and then go on to react with methane in a chain reaction, which produces several different compounds. The product of this reaction can be chloromethane, dichloromethane, trichloromethane or Tetrachloromethane and hydrochloric acid (HCl) or hydrogen halide.

Cracking is the breaking of long alkane chains (and other more complex organic molecules) into simpler smaller ones through the use of high heat, pressure and catalysts. This process​ ​involved​ ​heating​ ​the​ ​hydrocarbons​ ​to​ ​vaporise​ ​them. The​ ​vapours​ ​are then either​ ​passed​ ​over​ ​a​ ​hot​ ​catalyst​ ​(silica​ ​or​ ​alumina) or mixed​ ​with​ ​steam​ ​and​ ​heated​ ​to​ ​a​ ​very​ ​high​ ​temperature​ ​(temperature in​ ​the​ ​range​ ​of​ ​600-700 ̊C)​ ​so​ ​that​ ​thermal​ ​decomposition​ ​reactions​ ​can occur. The​ ​products​ ​of​ ​cracking​ ​include​ ​shorter​ ​chain​ ​alkanes​ ​and​ ​alkenes​ ​(or​ ​hydrogen)

Unsaturated​ ​=​ ​contain​ ​one​ ​or​ ​more​ ​C=C​ ​double​ ​bonds​ ​e.g.​ ​alkenes while saturated​ ​=​ ​contain​ ​no​ ​C=C​ ​double​ ​bonds​ ​e.g.​ ​alkanes. Unsaturated​ ​hydrocarbons​ ​react​ ​with​ ​bromine​ ​in​ ​an​ ​addition​ ​reaction, decolourising​ ​it​ ​as there is no more bromine (​orange​​ ​to​ ​colourless) and saturated​ ​hydrocarbons​ ​do​ ​not​ ​react​ ​with​ ​bromine​ ​and​ ​therefore​ ​the solution​ ​will​​ ​remain​ ​orange

an example of addition polymerisation of monomer units

Addition​ ​reactions involve​ ​the​ ​removal​ ​of​ ​C=C​ ​double​ ​bond as the C=C​ ​bond is​ ​very​ ​reactive​ ​and​ ​can​ ​easily​ ​react​ ​to​ ​form​ ​C-C. - alkene​ ​+​ ​bromine​ ​→​ ​dibromoalkane. E.g.​ ​Ethene​ ​+​ ​bromine​ ​→​ ​1,2-dibromoethane as the double bond breaks. • alkene​ ​+​ ​steam​ ​→​ ​alcohol, E.g.​ ​Ethene​ ​+​ ​steam​ ​→​ ​ethanol this reaction is called hydrogenation • alkene​ ​+​ ​hydrogen​ ​→​ ​alkane, E.g.​ ​Ethene​ ​+​ ​hydrogen​ ​→​ ​ethane

ethene gas obtained from cracking can be further reacted with water in the form of steam to produce ethanol in a process also known as hydration. This reaction is carried out at a temperature of about 550 °C and in the presence of a strong acid, such as sulfuric or phosphoric acid, which acts as a catalyst. Also, fermentation causes ethanol to be produced as yeast respires anaerobically taking glucose to produce ethanol and carbon dioxide.

Ethanol is highly flammable and can easily be ignited at temperatures lower than room temperature. It burns readily with oxygen with a clean blue flame and does not produce any soot, releasing a lot of heat energy

It is used as a solvent for substances that can not dissolve in water and is a solvent for perfume and makeup. Ethanol can also be used as a biofuel for cars.

Fermentation advantages: ▪ Renewable​ ​raw​ ​materials ▪ Warm,​ ​normal​ ​pressure​ ​(inexpensive) ▪ Little​ ​energy​ ​needed Fermentation disadvantages: ▪ A​ ​lot​ ​of​ ​workers​ ​needed ▪ Slow ▪ Impure​ ​–​ ​needs​ ​treatment Steam advantages: ▪ Continuous​ ​process​ ​(runs​ ​all​ ​the​ ​time) ▪ Few​ ​workers​ ​needed ▪ Fast ▪ Pure Steam disadvantages: ▪ Non-renewable​ ​raw​ ​materials ▪ High​ ​temperature​ ​and​ ​pressure​ ​(expensive) ▪ A​ ​lot​ ​of​ ​energy​ ​needed

It dissolves​ ​in​ ​water​ ​to​ ​produce​ ​an​ ​acidic​ ​solution, has a melting point of 17˚C and a boiling point of approximately 118 °C. It forms ice-like crystals just below 17 °C and in its pure form, is corrosive.