Hydrocarbons at Room Temperature

1. Hydrocarbons at Room Temperature • Liquid • Waxy 20 to 40 Carbons 40 or more Carbons • Gas • Methane • Ethane • Propane • Butane • Plastic 5 to 19 Carbons

2. Melting Point • As the length of hydrocarbons get longer, the Melting Point grows Higher. Why?

3. What other material properties change? • Viscosity • Hardness • Toughness • Flammability

4. Physical Properties of Hydrocarbons • The first four alkanes (C1 to C4) are all gases at room temperature. • Compounds from C5 to C17 are oily liquids. • Compounds greater than C17 are solids at room temperature and pressure. • As the number of carbon atoms increases, the molecules become larger and heavier. This also means that their melting points and boiling points increase. • Liquid alkanes are insoluble in water, are less dense than water. Alkanes are soluble in non-polar solvents.

5. Reactions of hydrocarbons • Complete Combustion (oxidation) reactions Alkanes, alkenes and alkynes burn in air reacting with the oxygen in air to produce carbon dioxide and water. CH4(g) + 2O2(g) ® CO2(g) + H2O(g) • Incomplete combustion (oxidation) reactions produces carbon monoxide and water vapour.

6. Reactions of alkanes • Substitution reactions Alkanes react with halogens in sunlight or at high temperature in a substitution reaction. Substitution continues if more halogens are present. Su S UV light

7. Alkanes

8. Reactions of the alkenes & alkynes • When alkenes or alkynes react with halogens they undergo addition reactions.

9. Naming hydrocarbons

10. Functional Groups

11. Functional groups • Functional groups are parts of molecules that result in characteristic features.

12. Esters • The carboxylic acids react with alkanols to form esters. Esters are a group of compounds which give the pleasant ‘fruity’ smell to various fruits. This is called a dehydration or esterification reaction.

13. Name and draw the expanded structural formula of the ester formed whenethanol reacts with propanoic acid. • .

14. Crude oil • Crude oil, also called petroleum, is a complex mixture of carbon and hydrogen (hydrocarbons), which exist as a liquid in the earth's crust. • The carbon and hydrogen in crude oil are thought to have originated from the remains of microscopic marine organisms that were deposited at the bottom of seas and oceans and was transformed at high temperature and pressure into crude oil and natural gas.

15. Petroleum Refining • Petroleum refining is the process of separating the many compounds present in crude petroleum. This process is called fractional distillation where the crude oil is heated; the various of the compounds boil at different temperatures and change to gases; and are later recondensed back into liquids. • The principle which is used is that the longer the carbon chain, the higher the temperature at which the compounds will boil.

16. Fractional distillation

17. properties The various components of crude oil have different sizes, weights and boiling temperatures and viscocity • bigger the molecule greater the intermolecular force • ... more viscous as the intermolecular attractive forces between molecules increases. • ... higher melting point as more vibrational kinetic energy is needed to overcome the intermolecular attractive forces holding the molecules together to form the crystals. • ... less flammable as they become less volatile, again due to increasing intermolecular forces.

18. Cracking • Cracking is the name given to breaking up large hydrocarbon molecules into smaller and more useful bits. This is achieved by using high pressures and temperatures without a catalyst(thermal cracking), or lower temperatures and pressures in the presence of a catalyst(catalytic cracking).