organic chemistry A-C

Question 1

hydrocarbons definition

Answer 1

compounds containing hydrogen and carbon atoms only

Question 2

aliphatic definition

Answer 2

molecules containing straight chains, branched chains, and rings (not benzene)

Question 3

aromatic definition

Answer 3

molecules containing benzene rings

Question 4

alkanes definition

Answer 4

hydrocarbons with only single bonds between carbon atoms - no new atoms can be added without first removing atoms

Question 5

alkenes definition

Answer 5

hydrocarbons which include carbon double bonds - new atoms can be added by turning double bond into single bond (saturation)

Question 6

homologous series definition

Answer 6

series of organic compounds with the same general formula and functional group (consecutive members of a series differ by CH2)

Question 7

functional group definition

Answer 7

a group of atoms responsible for the properties/reactions of a particular compound

Question 8

separation process in fractional distillation

Answer 8

• crude oil heated so its vaporised
• vapour passed into a tower which is hot at bottom and cold at top
• as vapour rises it cools
• molecules condense at different heights as they have different boiling points
• larger the molecule, lower down the column it condenses

Question 9

what happens to hydrocarbons as the chain gets longer

Answer 9

• become more viscous
• harder to ignite
• less volatile
• have higher boiling points

Question 10

what is reforming

Answer 10

the process of converting straight chain hydrocarbons into branched and cyclic molecules - using a platinum catalyst

Question 11

nomenclature rules

Answer 11

• name is based around name of longest hydrocarbon chain
• functional group indicated by prefix or suffix
• position of functional group given by number
• only include numbers if needed
• if two or more of same groups, di tri tetra penta hexa etc
• number separated by commas and groups listed in alphabetical order
• suffix for alkenes can go infront of other suffixes

Question 12

homolytic fission

Answer 12

even/symmetrical breaking of bonds
UV light has sufficient energy to break Cl2 bond

Question 13

heterolytic fission

Answer 13

uneven breaking of the bond
UV light does not have sufficient energy to cause this

Question 14

initiation

Answer 14

forms the radicals (using UV light)

Question 15

propagation

Answer 15

radical reacts with alkane (hydrogen lost from alkane and bonds to radical), THEN alkene (radical) reacts with halogen molecule to form halogenoalkane and radical

Question 16

termination

Answer 16

radicals react ( can be many different reactions)

Question 17

cis/trans

Answer 17

alkenes - cis same side, trans different side - carbon atoms must be attached to 2 diff groups and one group must be same

Question 18

E/Z

Answer 18

alkanes/alkenes - E- highest priority (highest atomic number) on diff sides, Z - highest priority on same side

Question 19

alkanes

Answer 19

single sigma bond, nonpolar, insoluble in water, unreactive, london forces, more branched lower BP

Question 20

alkenes

Answer 20

pi bond and sigma bond (pi more likely to react), cannot rotate

Question 21

cracking

Answer 21

produce short alkanes and alkenes (reactive) - thermal high temp and 70atm more alkenes, catalytic high temp 1-2atm branched chains into alkanes aromatics cyclics, zeolite used

Question 22

electrophilic addition alkene and hydrogen halide

Answer 22

electron moves from double bond to H+, electrons between hydrogen halide moves to halogen, intermediate formed of C+ and single bond, pair of electrons from negative halogen move to carbocation, electron pair attaches to form final product

Question 23

markovnikovs rule

Answer 23

When a compound HX is added to an unsymmetrical alkene, the hydrogen becomes attached to the carbon with the most hydrogens attached to it already.

• the carbocation with more alkyl groups is more likely to be formed as more stable - major - as electrons shift to the positive charge

Question 24

addition of hydrogen - hydrogenation/reduction conditions

Answer 24

alkene + hydrogen
Ni catalyst and high temperature

Question 25

addition of halogens

Answer 25

alkene + halogen Cl and Br react rapidly to form di-substitutes halogenoalkanes, Fl reacts explosively with small alkenes, reaction with iodine very slow

Question 26

addition of water - hydration conditions

Answer 26

alkene + steam H3PO4 and high temperature

Question 27

oxidation addition reaction conditions

Answer 27

alkenes + potassium manganate (VII) dilute H2SO4 used to test for alkenes (excess alkene purple colour disappears)