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Question 1

What is a structural isomer?

Answer 1

Same molecular formula, but different structural formula

Question 2

Definition of a radical

Answer 2

Species containing an unpaired electron.

Question 3

Definition of a electrophile

Answer 3

Electron deficient species that is attracted to electron rich species e.g Br2, Cl2, H-Br (accepts electrons)

Question 4

Definition of a nucleophile

Answer 4

Electron rich specie that is attracted to electron deficient species e.g. -OH, -CN, (donates electrons)

Question 5

meaning of the term saturated

Answer 5

Maximum number of H atoms/only single covalent bonds.

Question 6

Suggest why a branched chain isomer has a lower boiling point than a straight chain.

Answer 6

Branched chain have lower surface area. Therefore, less induced dipole-id forces between molecules. Therefore, lower boiling point.

Question 7

What type of isomer is but-1-ene compared to but-2-ene

Answer 7

Positional isomers since the position of the double bond has changed.

Question 8

Test for an alkene

Answer 8

Add aqueous bromine, electrophillic addition reaction. Orange brown turns to colourless.

Question 9

Define heterolytic fission

Answer 9

The breaking of a covalent bond where one atom takes both electrons from the bond, forming a cation and anion

Question 10

what is stage one of free radical substitution?

Answer 10

initiation stage

Question 11

what occurs In the initiation stage?

Answer 11

atom of an element (e.g chlorine) will undergo homolytic fission which produces a free radical.

Question 12

what is stage two of free radical substitution?

Answer 12

propagation stage

Question 13

what happens during the propagation stage?

Answer 13

C2H6 + Cl. → .CH2CH3 + HCl
chain reactions occur where the free radicals will react until they have replaced all hydrogen atoms from the carbon atom.

the free radical will attack a hydrogen atom and removes it from the carbon which creates a carbon radical next to the carbon and a new atom of hydrogen Cl for example

the carbon radical then reacts with the excess Cl to add a Cl to the carbon but also creates new one

Question 14

what is stage three of free radical substitution?

Answer 14

termination stage

Question 15

what happens during the termination stage?

Answer 15

two free radicals react together which can increase length of carbon chain
.CH2CH3 + Cl. → CH2ClCH3

Question 16

what condition is required for the initiation stage?

Answer 16

UV light must be present

Question 17

what type of bonds are present in alkenes?

Answer 17

double bonds = pi bonds 𝛑
single bonds = sigma bonds o~

Question 18

what bonds are present between one carbon and one hydrogen?

Answer 18

single, sigma bonds

Question 19

describe bonding between carbon atoms and ethene

Answer 19

carbon atoms are double bonded together by pi bonds which shows the overlap of p orbitals and the carbons are also single bonded to two hydrogens each with sigma bonds which show an overlap of s orbitals

Question 20

what orbital does a pi bond signify?

Answer 20

p-obital

Question 21

what orbital does a sigma bond signify?

Answer 21

s-orbital

Question 22

what reactions do all alkenes undergo?

Answer 22

electrophilic addition reactions

Question 23

what is step one to do in this reaction?

Answer 23

identify the electrophile and the nucleophile, place sigma o~+ and o~- next to them. draw a curly arrow to the negative charged element to show movement of electrons and a curly arrow pointing at the positive charged element signifying it has joined the compound

Question 24

what happens in step two of this reaction?

Answer 24

after the positive element has joined the atom the negatively charged one gains two electrons and shows a full minus charge. a carbon in the main compound will have a full plus by it to attract the negative element

Question 25

what is step three of this reaction?

Answer 25

the remaining negative element joins the main compound on where the positive carbon was

Question 26

if electrophilic addition produces more than one possible product, which do we use and why?

Answer 26

the major product which is the carbocation with the most alkyl groups (CH3). this is because if for example it joins onto a propene then putting the extra element e.g Br onto carbon two will mean it will have two alkyl groups to stabilise it

Question 27

what are the different carbocations?

Answer 27

• primary - bonded to the first carbon
  secondary - bonded to the second carbon
  tertiary - bonded to the third carbon

Question 28

what are the standard conditions of hydrogenation?

Answer 28

temperature of 150c
nickel catalyst
H2 available

Question 29

what process do alkenes under go that is poly

Answer 29

addition polymerisation

Question 30

names of ethene after being polymerised

Answer 30

poly ethene (always add poly at start)

Question 31

draw the repeating unit of tetrafluroethene and name it -

Answer 31

polytetrafluroethene

Question 32

how to calculate empirical formula using C4H5Cl

Answer 32

divide using smallest number, in this case one, so it remains C4H5Cl

Question 33

calculate empirical formula of C6H12

Answer 33

divide all by 6 so it would become CH2

Question 34

does a double bond contain high electron density and high negative energy?

Answer 34

yes

Question 35

calculate empirical formula using percentages.

Answer 35

firstly divide percentages by the elements atomic mass e.g carbon = 12

then this will give you the mols present in each element
use the smallest number of mols and use that number to divide the other mols by this one
this will give you a set of numbers e.g 1,1 and 2
so you would write XY2Z

Question 36

Why does E-Z isomerism occur?

Answer 36

restricted rotation about the planar carbon carbon double bond

Question 37

where are the priority groups on a z isomer?

Answer 37

on the same side going across (at top across or at bottom across)

Question 38

on the opposite side going across

Answer 38

on the opposite side going across