Chapter Nine : Properties and reactions of organic compounds

Question 1

Intermolecular forces

Answer 1

Dispersion
Dipole-Dipole
Hydrogen

Question 2

Dispersion forces

Answer 2

Non-polar molecules
Electrons are momentarily distributed unevenly inducing a temporary dipole
Weak forces
Increase as chain length increases
Decreases with branching

Question 3

Dipole-Dipole

Answer 3

Polar molecules
The partial positive charge on one attracts the partially negative charge on the other
Stronger than dispersion

Question 4

Hydrogen bonding

Answer 4

Hydrogen bonds to FON

Stronger than dispersion and dipole-dipole

Question 5

Structural isomers

Answer 5

Chain isomers - different branching in carbon chain
Positional isomers - different position of functional group
Functional isomers - Same atoms different functional groups

Question 6

Stereoisomers

Answer 6

Cis isomers - when the groups are on the same side
Trans isomers - when groups are on opposite sides
Enantiomers - non-super imposable mirror images with a chiral centre

Question 7

Alkane properties

Answer 7

Non-polar
As size increases dispersion forces increase, so MP and BP increases
As branching increases dispersion forces decrease and BP
Insoluble in water
Viscosity increases in size decreases as temp increases
Smaller ones have lower flashpoint

Question 8

Flashpoint

Answer 8

Is the lowest temperature at which a liquid gives off enough vapour to start burning at its surface with the application of ignition source

Question 9

Alkene/alkyne properties

Answer 9

Alkenes are more reactive than alkanes
Alkynes have low polarity
Highly flammable

Question 10

Alcohol properties

Answer 10

Higher BP due to hydrogen bonding
BP increases as chain length increases
Smaller alcohols are soluble in water
Volatility decreases with length
Viscosity increases with length

Question 11

Carboxylic acid properties

Answer 11

Smaller acids are soluble in water
Higher BP than alkanes/alcohols due to H bonds
Solubility decreases with chain length

Question 12

Aldehydes and ketones properties

Answer 12

Volatile compounds
Solubility decreases with chain length
Higher BP than alkanes but lower than alcohols or acids

Question 13

Ester properties

Answer 13

Lower BP than acids

Small esters are soluble in water

Question 14

Amine properties

Answer 14

Weak base that accepts protons
Lower BP than alcohols
Solubility decreases with chain length

Question 15

Amide properties

Answer 15

Have a higher BP/MP

Soluble but less soluble than amines/COOH

Question 16

Reactions of alkanes

Answer 16

Combustion - reacts w O2 to for CO2,CO and H2O
Substitution - reacts with halogens in presence of UV light
Cracking - Using heat to break larger molecules to smaller molecules

Question 17

Reactions with alkenes

Answer 17

Combustion - reacts w O2 to for CO2, CO and H2O
Addition - double bond breaks when electronegative atom is reacted. H2 requires Pt, Pd or Ni catalyst
Forming alcohols - steam in presence of H3PO4 catalyst
Addition polymerisation - Adding monomers to make polymers

Question 18

Alcohol reactions

Answer 18

Combustion - reacts w O2 to form CO, CO2 and H2O
Substitution - Removing OH group and subbing it with a different functional group
Oxidation (1) - Oxidises to aldehyde then COOH in presence of H+/MnO4 or H+/Cr2O7-
Oxidation (2) - oxidises to ketones in presence of H+/MnO4 or H+/Cr2O7-

Question 19

Haloalkanes reactions

Answer 19

Forming alcohols - reaction NaOH or KOH with haloalkane will give an alcohol

Question 20

Ester reactions

Answer 20

Condensation - Reaction between COOH and OH to form esters in presence of heat/sulfuric acid
Hydrolosis - When water is added to an ester to split it back into OH and COOH using heat and dilute acid

Question 21

Carboxylic acid reactions

Answer 21

Hydrolyse - seperate in water to become COO-

Acid-base - react with bases, Mg and metal carbonates

Question 22

COOH and amine reactions

Answer 22

Small amines act as base, COOH donates protons

COOH + NH2 > ammonium salt >(heat/dehydration) > amide + water