Chapter 21 - Fuels & Heats of Reactions

The study of the compounds of carbon

A compound that only contains hydrogen and carbon

Coal, natural gas (methane) & petroleum

Fuels that were formed from the remains of plants and animals that lived millions of years ago

alkanes alkenes alkynes

○ All atoms are linked together by single bonds ○ Names all end in -ane ○ All prepared in the same way ○ All have similar chemical properties ○ First four are gases, next twelve are liquids, rest are waxy solids ○ Are saturated compounds

One in which there are only single bonds between atoms in a molecule

CₙH₂ₙ₊ₙ

Defined as: • a series of compounds of similar chemical properties • showing gradations in physical properties • having a general formula for its members • each member having a similar method of preparation • each member differing from the previous member by a CH₂ unit

Compounds with the same molecular formula but different structural formulas

• Identify the longest chain of carbon atoms • Identify the functional group • Number the carbon chain starting from the end that gives the substituents the lowest possible number • Indicate the type and position of substituents, and if multiples exist we use prefixes like di, tri etc • Name all substituents in alphabetical order

• Contain at least one double carbon bond in a chain • Are unsaturated • Names end in ene • First three are gases, next eleven are liquids, rest are waxy solids • Boiling points increase as you go down the series

One that contains one or more double or triple bonds between the atoms in the molecule

CₙH₂ₙ

• Identify the longest chain of carbon atoms containing the c=c bond • Identify the functional group • Number the carbon chain starting from the end that is closest to the c=c bond • Indicate the type and position of substituents, and if multiples exist we use prefixes like di, tri etc • Name all substituents in alphabetical order

• Pour ethanol into a boiling tube and add glass wool • Place a small piece of aluminium oxide (Al₂O₃) half way • Gently heat • Discard first tube and collect five more • Lift tubing from water and turn off bunsen

• Bubbles of gas collect in the gas tube • Aluminium oxide (Al₂O₃) becomes hot, heat reaches the ethanol which changes to vapour, passes over the hot aluminium oxide (Al₂O₃) and is dehydrated to form ethene

To prevent suck back → as air in the boiling tube cools, a vacuum is created and water is sucked vack to fill the space. The cold water could cause the hot glass to crack and break

• Colourless gas • Sweetish smell • Insoluble in water • Soluble in cyclohexane

…yellow luminous flame and is slightly smokey

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

The colour changes from orange to colourless

Colour changes from purple to colourless

Fruits produce ethene naturally to help them ripen. Also used to make plastic e.g polythene