Organic Chemistry (I and II and III)

Question 1

What is the general formula?

Answer 1

The algebraic formula that can describe any member of a family of compounds

Question 2

What is the empirical formula?

Answer 2

The simplest whole number ratio of atoms of each elements in a compound

Question 3

What is the molecular formula?

Answer 3

The actual number of atoms in each element in a molecule

Question 4

What is the structural formula?

Answer 4

Shows the arrangement of atoms carbon by carbon with attached functional groups and hydrogens (doesn’t show bonds)

Question 5

What is the skeletal formula?

Answer 5

Shows the bonds of the carbon skeleton and any functional groups only. No C atoms or H atoms are shown

Question 6

What is the displayed formula?

Answer 6

Shows how all the atoms are arranged and shows all the bonds between them

Question 7

What is the definition of homologous series?

Answer 7

A group of organic compounds that have the same functional group and general formula. Members of a homologous series differ by CH2

Question 8

What is a functional group?

Answer 8

a group of atoms in a molecule which present in molecules causes them to have similar chemical properties

Question 9

What is an addition reaction?

Answer 9

joining two or more molecules together to form a larger molecule

Question 10

What is a polymerisation reaction?

Answer 10

joining together lots of a simple molecules to form a giant molecule

Question 11

What is chain isomerism?

Answer 11

Compounds with same molecular formula but different structures of the carbon skeleton (e.g. pentane and 2-methylbutane)

Question 12

What is position isomerism?

Answer 12

compounds with same molecular formula but different positions of the same functional group on the same carbon skeleton (e.g. 1-bromopropane and 2-bromopropane)

Question 13

What is functional group isomerism?

Answer 13

compounds with the same molecular formula but with atoms arranged to give different functional groups (e.g. cyclohexane and hexane)

Question 14

What is stereoisomerism?

Answer 14

Stereoisomers have the same structural formulae but have a different spatial arrangement of atoms.

Question 15

How do E-Z stereoisomers arise?

Answer 15

There is restricted rotation around the C-C double bond in alkenes
There are two different/groups atoms attached to both ends of the double bonds

Question 16

What is reforming?

Answer 16

Turns straight chain alkanes and cyclic alkanes and aromatic hydrocarbons to burn more cleanly and give a higher octane number

Question 17

What is cracking?

Answer 17

The conversion of large hydrocarbons to smaller molecules by breakage of C-C bonds

Question 18

What are the economic reasons for catalytic cracking?

Answer 18

Shorter C chains are more in demand than larger fractions

Products are more useful or valuable

Question 19

Are alkanes saturated or unsaturated?

Answer 19

Saturated because they only contain single c-c bonds

Question 20

How are alkanes obtained?

Answer 20

Fractional distillation-crude oil is vaporised with lowest temp at top and highest temp at bottom and each chain separates by boiling point

Question 21

What are the conditions of catalytic cracking?

Answer 21

zeolite catalyst and 450 degrees

Question 22

What does catalytic cracking form? And the advantage?

Answer 22

forms aromatic compounds- burns more easily

Question 23

Conditions for thermal cracking? And what does it form?

Answer 23

high temp and high pressure and produces alkenes

Question 24

What does incomplete combustion form? and what is the disadvantages?

Answer 24

SO2, NO2 or NO3

can cause acid rain or respiratory problems

Question 25

What is the most dangerous thing incomplete combustion can form?

Answer 25

CO | toxic, binds to haemoglobin irreversibly so O2 cannot bind

Question 26

What can be used to fix the products of incomplete combustion?

Answer 26

catalytic converter

Question 27

Reactions of a catalytic converter?

Answer 27

2NO------>N2+O2 | 2NO+2CO----->N2+CO2

Question 28

What is free radical substitution used for?

Answer 28

formation of halogenoalkanes from alkanes

Question 29

What is a free radical?

Answer 29

A species with a single unpaired electron

Question 30

What is an initiation reaction? An example?

Answer 30

Forms two radical species from zero radicals by homolytic fission, eg: X2--------> X. + X.

Question 31

What is a propagation reaction?

Answer 31

One radical in and one radical out, eg: ch4 +Cl..----> HCl + CH3.. CH3.. +Cl2 -------> CH3Cl +Cl...

Question 32

What is a termination reaction?

Answer 32

two radicals in and zero radicals out | eg. Cl..+Cl..------>Cl2

Question 33

What are the disadvantages of free radical substitution?

Answer 33

Low yield because of the other products produced

Question 34

Describe the bonding in ethene

Answer 34

Sigma bonds are single bonds and are formed by end on overlap of orbitals Each p orbital has one free electron left and the p orbitals overlap to form regions of negative charge above and below the C atoms-----pi bonds

Question 35

Why do addition reactions occur in alkenes?

Answer 35

Because the electrons in the pi bond can be used to form bonds with attacking molecules and these produce molecules with only sigma bonds which are more stable

Question 36

What are electrophiles?

Answer 36

A molecule which receive a lone pair of electrons

Question 37

What happens in hydrogenation of alkene reaction?

Answer 37

ch2=ch2+ H2------> ch3-ch3 (ethane)

Question 38

Whats the use of hydrogenation reactions?

Answer 38

used to convert vegetable oils into solid magarine

Question 39

Conditions of hydrogenation?

Answer 39

Nickel catalyst and heat

Question 40

What happens in hydration of alkene reaction?

Answer 40

ch2=ch2+ H20------->ch3-ch3OH (ethanol)

Question 41

Conditions of hydration?

Answer 41

``` Water vapour (high temp) H3PO4 catalyst ```

Question 42

Oxidation of alkene produces what? (reaction)

Answer 42

diol | ch2=ch2 + [O]+ h20------> ch2OH-ch2OH (ethane-1,2-diol)

Question 43

Oxidising agent in oxidation reaction of alkene

Answer 43

KMno4

Question 44

Oxidation of alkene observations?

Answer 44

purple to colourless

Question 45

3 ways to extend the carbon chain

Answer 45

1. add CN- to a haloalkane to produce a nitrile 2. add HCN and KCN to a carbonyl compound to produce hydroxynitrile 3. Acylation/alkylation reactions of a Benzene ring

Question 46

How to form a Grignard reagent?

Answer 46

Add Magnesium in dry ether to a bromoalkene and heat under reflux

Question 47

Reaction of Grignard reagent and CO2

Answer 47

R-MgBr + CO2-----> R-COOH (carboxylic acid) | (extend the carbon lengths)

Question 48

Reaction of Grignard reagent and methanal

Answer 48

R-MgBr + HCHO---> R-CH2-OH (1' alcohol) | extend carbon chain

Question 49

Reaction of Grignard reagent and other aldehydes

Answer 49

R-MgBr + R'CHO-----> R-R'-CHOH (2'alcohol)

Question 50

Reaction of Grignard reagent and ketones

Answer 50

R-MgBr + R'COR''-----> R-R'-R'-COH (3' alcohol)

Question 51

What is the formation of electrophile reaction for nitration of Benzene?:

Answer 51

h2so4+hno3---> no2(+) + h2o +hso4-

Question 52

why can phenol be nitrated under milder conditions than benzene ?

Answer 52

oxygen on OH group has a delocalised lone pair of electrons | these electrons increase electron density of ring making it more susceptible to electrophiles

Question 53

why are hydroxynitriles not optically active?

Answer 53

A racemic mixture is formed because THE MOLECULE AROUND C=O is planar

Question 54

what are the advantages of using acyl chlorides to make an ester

Answer 54

produces a higher yield of ester no catalyst is needed and reaction goes into completion

Question 55

why is it is faster to use an acyl chloride to make an ester

Answer 55

Cl- is a better leaving group | C-Cl is a weaker bond

Question 56

how to name esters?

Answer 56

the first part, the -yl group comes from the alcohol the second part- the -onoate part comes from the carboxylic acid OH comes from the alcohol H comes from carboxylic acid

Question 57

how to name amines?

Answer 57

(alkyl)- amine e.g propylamine, methylamine if amine is secondary, then you name you put N- then the smallest akyl group eg. N-ethylpropylamine

Question 58

why are secondary amines better bases than primary amines?

Answer 58

because the nitrogen is surrounded by more akyl groups which are electron releasing they increase the electron density

Question 59

reaction of acyl chlorides with amines

Answer 59

produces secondary amides

Question 60

why do amino acids have a high melting point

Answer 60

amino acids exists as zwitterions | they have an ionic interaction between DIFFERENT zwitterions which requires a lot of energy to break this bond

Question 61

reaction of hydrolysis of nitriles

Answer 61

CH3CH2CN + H(+) + 2H2O ----> CH3CH2COOH + NH4+

Question 62

why is the structure of benzene more stable

Answer 62

there are delocalised pi electrons around the ring which give greater stability

Question 63

what is the criteria for using cis-trans naming system

Answer 63

2 of the groups have to be the same

Question 64

what ensures a greater yield of an aldehyde when you are carrying out an oxidation of alcohols reaction

Answer 64

distill off the product | make sure a limited amount of oxidising agent used

Question 65

how to carry out a chromatogram for amino acids

Answer 65

1. place spot on paper 2. marker spot of known amino acids 3. run in solvent 4. spray on ninhydrin 5. marker spots should have similar rf values

Question 66

why is a carbocation intermediate used for tertiary halogenoalkanes

Answer 66

it is a more stable structure methyl groups stabilise charge of carbocations steric hinderance inhibit formation of transition state

Question 67

why do some alkenes have e-z isomers

Answer 67

because each carbon atom has two groups attached | and there is restricted rotation around the C=C bond

Question 68

why is Benzene stable?

Answer 68

there are delocalised pi electrons around the ring and it undergoes electrophilic substution