Organic compounds Flashcards
carbon compounds are NOT
allotropes of carbon (diamond, graphite etc.) because they are carbon element forms
Hydrocarbons
Organic compounds consisting of C and H atoms only
Homologous series
Series of compounds with similar chemical properties
each member differs from the previous one by a CH2
Alkanes
CnH2n+2
saturated hydrocarbon
Saturated hydrocarbons
have only single covalent bonds and maximum number of hydrogen atoms around a carbon atom
Alkenes
CnH2n
Double bond present between two carbon atoms
unsaturated hydrocarbon
Why alkene an unsaturated hydrocarbon?
Double bond between two of the carbon atoms means that they have less hydrogen than the maximum amount possible
Alkyl group
H atom is eliminated from an alkane and alkyl group is formed
CnH2n+1
name ends “yl”
Functional group hydroxy
Homologous series name: alcohol
Formula: R-O-H
Functional group carboxy
Homologous series name: carboxylic acids
Formula: R-COOH
Functional group halides
Homologous series name: Alkyl halides/ halo alkanes
Formula: R-X (Cl, Br, I, F)
Functional group amino
Homologous series name: amines
Formula: R-NH2
Functional group ester
Homologous series name: Esters
Formula: R-COO-R
Hydrocarbon intermolecular forces
All hydrocarbons are non polar so intermolecular forces are dispersion only
Higher the Mr of the hydrocarbon, stronger the dispersion forces
More the branches of the isomer, molecules become far apart and dispersion forces become weaker so lower MP and BP (lower viscosity)
Linear isomer intermolecular forces
Linear isomers are stacked up closely, therefore stronger dispersion forces
Structural isomers
Carbon compounds which have the same molecular formulas but different structural arrangements
similar chemical properties but differ in some physical properties
Compounds with smaller molecules
more volatile, evaporate easily, low viscosity
Functional group
Atom or group of atoms that influence the properties of the compounds forming a homologous series
Compounds with the same functional group…
Behave the same way chemically
Alkyl halides/halo alkanes
A hydrogen atom in an alkane is replaced with a halogen to form a halo alkane
Polar- intermolecular forces are dipole-dipole and dispersion
have greater physical properties compared to hydrocarbons due to stronger dipole-dipole attractions
Alcohols
Polar- hydrogen bonds and dispersion forces
forces between molecules in an alcohol are much stronger than an alkane
Electronegativity of nitrogen is less than oxygen therefore amine has weaker H-bonding than alcohol
Amines
Polar
H-bonding operates in addition to dispersion forces
Boiling temperature of amine increases as the size of the molecule increases (Mr)
Electronegativity of nitrogen is less than oxygen therefore amine has weaker H-bonding than alcohol
Carboxylic acid
polar Hydrogen bonding and dispersion forces Boiling temp increases as dispersion force strength increases as Mr increases Esters and carboxylic acids are isomers always no. 1 branch in naming
Esters
polar
Dipole-dipole and dispersion
Formed by reacting carboxylic acids and alcohol in presence of sulfuric acid liquid catalyst
although esters are polar, they cannot form H-bonding thus they have lower BP
Esters and carboxylic acids are isomers
H-bonds in alcohols and carboxylic acids
H-bonds stronger in carboxylic acids than alcohols due to dimerisation
therefore BP of RCOOH are greater
Condensation reactions (Esterification)
Occur when two functional groups react to form a new functional group, with the loss of a small molecule
catalyst- H2SO4
OH of carboxylic acid and H of alcohol form H2O
Complete combustion
excess 02 (g) Products: CO2(g) and H2O
Incomplete combustion
limited supply of air (O2)
Products: CO (g) and H2O
Balancing combustion reactions
start by balancing the C atoms then H atoms and then O atoms
Alkane formula
CnH2n+2
Alkene formula
CnH2n
Alkyne formula
CnH2n-2
Halo alkane formula
CnH2n+1X
Alcohol formula
CnH2n+1OH
Amine formula
CnH2n+1NH2
Carboxylic acid formula
CnH2n+1COOH
