ITOC and Alkanes

describe alkanes

saturated hydrocarbons

what is meant by a homologous series

• a group of organic compounds with the same functional group, same general formula and similar chemical properties.

• they differ by a CH2 unit each time

what is the major use of alkanes

fuels

what is petroleum 

a mixture containing mostly alkane hydrocarbons that can be separated by fractional distillation 

what is meant by unsaturated

contains one or more C=C double bonds

what is meant by saturated

contains only C-C single bonds

what is a fraction

a group of molecules with a similar chain length, Mr and boiling points 

what is fractional distillation

a method of separating crude oil fractions according to their boiling points 

what is a hydrocarbon made from

only hydrogen and carbon

describe the stages of fractional distillation

• crude oil is heated to 350*C, it vaporises and enters the bottom of the column

• the top of the column is cooler than the bottom- negative temperature gradient

• fractions are separated because of their different boiling points

• low boiling point fractions are small molecules/ small Mr are collected at the top of the column

• high boiling point fractions are big molecules/ high Mr are collected at the top of the column

what is the theory behind fractional distillation

• physical process (not chemical)

• separation occurs according to similar boiling point

• weak IMF’s are overcome

• strong covalent bonds are not broken

what happens during cracking

strong C-C covalent bonds are broken

state the economic basis of cracking

• the demand for short chain hydrocarbons is greater than the supply produce from fractional distillation

• cracking breaks down longer, less useful (less profitable) hydrocarbons into shorter more useful, (profitable) products

if asked to write a cracking equation, what is formed

one alkane and one or more alkene/s

what are the conditions and major product of thErmal cracking

• high temperature and high pressure (no values needed)

• alkEnes

what is the major use of the products of thErmal cracking

making polymErs

what are the conditions and major product for cAtylitic cracking 

• high temperatures 

• slight pressure

• zeolite catalyst 

• AlkAnes and Aromatics

what is the major use of the products of cAtu