Unit eight JCL

Question 1

how is a sigma bond formed

Answer 1

directly between two carbon atoms by the direct overlap of p orbitals

Question 2

how is a pi bond formed

Answer 2

a pi bond is formed above and below the plane of carbon atoms by the sideways overlap of p orbitals

Question 3

why is a pi bond easier to break than a sigma bond

Answer 3

a pi bond is more likely to break as it has a lower bond enthalpy compared to sigma bonds

Question 4

why are alkenes insoluble in water

Answer 4

alkenes are non-polar and water is polar

Question 5

why do alkene boiling points increase with chain length

Answer 5

chain length increases –> more points of contact –> more induced dipole-dipole interactions

Question 6

define the term unsaturated

Answer 6

having carbon–carbon double or triple bonds and therefore not containing the greatest possible number of hydrogen atoms

Question 7

what are the strongest intermolecular forces experienced by alkenes

Answer 7

induced dipole-dipole interactions

Question 8

general formula for an alkene

Answer 8

CnC2n

Question 9

what shape and bond angle do alkenes have around the C=C bond

Answer 9

120

trigonal planar

Question 10

if an alkene has only one C=C bond, what shape and bond angle do the other carbons have along the chain

Answer 10

109.5

tetrahedral

Question 11

isomerism definition

Answer 11

isomerism is where two or more compounds have the same molecular formula but a different arrangement of atoms

Question 12

what are the two types of isomerism

Answer 12

stereoisomerism and structural

Question 13

what is stereoisomerism

Answer 13

stereoisomerism occurs in compounds with the same structural formula but a different arrangement in space.
the pi bond in alkenes restricts the rotation of the molecule potentially causing E/Z isomerism to occur

Question 14

what is required for E/Z isomerism to occur

Answer 14

a c=c double bond

each carbon is bonded to two different atoms/groups

Question 15

why do alkanes not show stereoisomerism?

Answer 15

they don’t have pi bonds to restrict rotation

Question 16

if a stereoisomer has two identical groups on the same plane of the molecule is it an E or Z isomer

Answer 16

Z isomer

Question 17

if a stereoisomer has two identical groups on the opposite plane of the molecule is it an E or Z isomer

Answer 17

E isomer

Question 18

what are Cis-Trans isomers

Answer 18

Cis-Trans isomers are a type of E/Z isomer where two of the substituent groups on the c=c bond are the same

Question 19

what is an addition reaction

Answer 19

tow reactants combine to form one product

Question 20

name the compound formed when ethene reacts with hydrogen

Answer 20

ethane

Question 21

name the compound formed when ethene reacts with hydrogen chloride

Answer 21

chloroethane

Question 22

name the compound formed when ethene reacts with water

Answer 22

ethanol

Question 23

name the compound formed when ethene reacts with bromine

Answer 23

1,2-dibromoethane

Question 24

what are conditions for hydrogenation

Answer 24

Nickle catalyst , 150C

Question 25

what are the conditions for bromination

Answer 25

room temperature and pressure

Question 26

what are the conditions for Hydration

Answer 26

H3PO4, 300C, 6MPa

Question 27

what is an electrophile

Answer 27

an electron pair donor

Question 28

what does a curly arrow represent

Answer 28

the movement of a pair of electrons

Question 29

what does markovnikov's rule state

Answer 29

the hydrogen being added bonds to the carbon with the most hydrogens present in the major product

Question 30

what stabilises a carbonium ion

Answer 30

the induction effect of adjacent alkyl groups | the ability of alkyl groups to donate electrons

Question 31

what is a monomer

Answer 31

a small molecule that can join together with other monomers to form a polymer

Question 32

what is a polymer

Answer 32

a long molecule formed from lots of repeating units (monomers)

Question 33

what is an addition polymer

Answer 33

a type of polymer formed from lots of alkenes joining together

Question 34

what is a repeat unit

Answer 34

the part of a polymer that repeats (similar to a monomer but the double bond has been broken)

Question 35

are alcohols polar or non-polar

Answer 35

polar

Question 36

equation for the combustion of alcohols

Answer 36

Alcohol + oxygen --> Carbon Dioxide + water

Question 37

what do you get when you reflux a primary alcohol with the oxidising agent of acidic potassium dichromate

Answer 37

Carboxylic acid

Question 38

what do you get when you distill a primary alcohol with the oxidising agent of acidic potassium dichromate

Answer 38

Aldehyde

Question 39

what do you get when you reflux a secondary alcohol with the oxidising agent of acidic potassium dichromate

Answer 39

Ketone

Question 40

what does dehydration mean

Answer 40

removal of water

Question 41

what is the colour change for the oxidising agent acidic potassium dichromate

Answer 41

orange --> green

Question 42

what is a haloalkane

Answer 42

a compound in which a halogen has replaced at least one of the hydrogen atoms in an alkane chain

Question 43

what is the general formula for a haloalkane

Answer 43

CnH2n+1X

Question 44

define nucleophilic substitution

Answer 44

a type of substitution reaction in which a nucleophile is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a covalent bond

Question 45

which is more important, bond enthalpy or polarity

Answer 45

bond enthalpy

Question 46

what is the formula of ozone

Answer 46

O3 molecules

Question 47

what does CFC stand for

Answer 47

Chlorofluorocarbons

Question 48

what happens when a CFC comes into contact with UV (equation)

Answer 48

CCl2F2 --uv--> •CClF2 + Cl•

Question 49

how do CFCs break down the ozone layer (equation)

Answer 49

Cl• + O3 --> ClO• + O3 | ClO• + O3 --> Cl• + 2O2

Question 50

are CFCs inert?

Answer 50

yes