9.1 Carbon Compounds

Organic compounds  contains C and H (often combined w/ O and N) – C-C bonds and C-H bonds  There are millions of organic compounds = more than 90% of known compounds  C has 4 valence e-  lots of options for bonds  4 single bonds  2 single + 1 double  2 double  1 triple + 1 single

Forms of Carbon Diamond graphite Buckminsterfullerene

Triangular pyramid Hexagonal cylinder

 A network solid  In layers  Ball made of hexagons  Rigid, compact, strong  Within layers strong and pentagons structure covalent bonds connect C  Large + hollow spheres,  Covalent bonds make a  Between layers weak bonds cages of C single molecule  slide each other  soft +  Surface of alternating  Good for cutting, slippery pentagons + hexagons grinding, drilling tools  Good lubricant for metals  C60  Pencil “lead” = mixture of  Found in soot + graphite + clay  leaves meteorites marks on paper (erasable) Hydrocarbon =Organic compound made of H + C – properties determined by # of C + arrangement of atoms Saturated hydrocarbons Unsaturated hydrocarbons Alkanes – single bonds C-C (-ane) Alkenes – double bond C=C Alkynes –triple bond C≡C (-yne) CnHsn+2 (-ene) w/ 1 double bond CnH2n w/ 1 triple bond CnH2n-2 ethyne

propyne

1 – meth- 6 – hex- 2 – eth- 7 – Sept- 3 – prop- 8 – oct- 4 – but- 9 -non- 5 – pent- 10 -deca- Saturated hydrocarbons – only single bonds 1) straight chains - see above table in alkane column

 Methane (CH4) in cow’s stomach can break down cellulose in grass  Methane + Propane = gases

 Pentane(C5H12) + octane (C8H18) = liquids  More carbon atoms  higher boiling points

2) branched chains - isomers of straight chains (isomer – same molecular formula, different structural formula)

isobutane (C4H10)

 # of isomers increases when # of carbon of alkanes increases: ex) octane (C8H18) has 18 isomers – decane (C10H22) has 75 isomers  Boiling pt of butane -0.5ºC; boiling pt of isobutene = -11.7ºC

3) Rings – C-C-C bonds  only 2 H connected to each C = “cyclo-“

cyclobutane (C4H8) – 2 less H than C4H10

cyclopentane (C5H10) – 2 less H than C5H12 Unsaturated Hydrocarbons – alkenes, alkynes, aromatic hydrocarbons

Alkenes Alkynes Aromatic Hydrocarbons  double bonds C=C  Double bonds C≡C  Ring structure (cyclical)

 C2H4 controls the rate at  C2H2 =ethyne =  Strong aromas or odors which fruits (ex. acetylene  alternating single and double Tomato) ripens; reacts  Most reactive bonds but six bonds are identical chemically to produce hydrocarbon ex) C6H6 plastic (garbage bags, compounds  milk jugs) acetylene + oxygen  oxyacetylene torch (high temperature 3500ºC)

C6H6 (benzene)

Fossil Fuels - remains of animals + plants from millions of years ago  turned into deposits of hydrocarbons Coal Natural gas petroleum  Giant tree ferns + other  Remains of marine  remains of marine plants buried in swamps organisms organisms  Mostly aromatic  Main component =  pumped from deep hydrcarbons methane (CH4) = beneath Earth’s surface  High molar masses compound produced by  composed of long-  High ratio of carbon to cow’s digestion of grass branched alkanes and hydrogen  more soot  Also contains ethane, alkenes when burning propane, isomers of  must separated into butane simpler mixtures  distributed by (=fractions) –gasoline, underground pipes heating oil  energy for heating +  fractional distillation – cooking, production of using different boiling electricity points (=condensing pts) –  found along w/ deposits of separate mixtures – coal + petroleum petroleum gas, gasoline, kerosene, heating oil, lubricating oil Combustion of fossil fuels  complete combustion (burn completely) C3H8 + 5O2  3CO2 + 4H2O (propane + oxygen  carbon dioxide + water Burning fossil fuels  more carbon dioxide, sulfur dioxide, nitrogen oxides (S, N in fossil fuels + O2)

 incomplete combustion (not enough oxygen, so burn incompletely) C3H8 + 7O2  6CO + 8H2O CO (carbon monoxide) = deadly, colorless, odorless  inhaled + absorbed by blood  stops hemoglobin from taking O2 to cells Tiny particles of C  heart + lung problems

 acid rain rain is usually acidic (pH 5.6); w/ carbonic acid (H2CO3 from carbon dioxide), sulfuric acid (H2SO4), nitric acid (HNO3)  pH of rain lower (=more acidic)