Organic Chemistry Reactions

Question 1

Combustion

Answer 1

alkanes, alkenes, alcohols + oxygen = CO2 + H20

exothermic reactions

Question 2

Halogenation (sub)

Answer 2

alkanes + X2 = haloalkanes + HX
substitution
condition: in the presence of ultraviolet light or heat

Question 3

Hydrolyses

Answer 3

haloalkanes + XOH = alcohols + XX
substitution
condition: heat under reflux in a dilute alkali solution

Question 4

Hydrogenation

Answer 4

alkene + H2 = alkane
addition
condition: alkane dissolved in an organic solvent with a Pt, Pd or Ni catalyst in an H2 atmosphere

Question 5

Halogenation (add)

Answer 5

alkene + X2 = haloalkane
addition
decolourisation of bromine water by an alkene is used to distinguish alkene from alkane

Question 6

Hydrohalogenation

Answer 6

alkene + HX = haloalkane
addition
condition: no water may be present

Question 7

Hydration

Answer 7

alkene + H2O = alcohol
addition
condition: steam and suitable catalyst, eg H3PO4

Question 8

Dehydrohalogenation

Answer 8

haloalkane = alkene + HX
elimination
condition: hot concentrated solution of NaOH or KOH in an ethanol solvent (absence of water)

Question 9

Dehydration

Answer 9

alcohol = alkene + H20
elimination
condition: acid catalysed dehydration - heating of alcohol with excess of concentrated H2SO4 or H3PO4

Question 10

Cracking

Answer 10

large hydrocarbons breaks into smaller molecules
elimination
condition: thermal cracking: high pressures and temperatures without catalyst
catalytic cracking: lower temperatures and pressures in the presence of a catalyst