2.4 - Organic Compounds

Question 1

What is the general formula

Answer 1

the ratio of C:H atoms and functional groups

Question 2

What is the empirical formula

Answer 2

the simplest whole number of elements in a compound

Question 3

What is the molecular formula

Answer 3

actual number of atoms of each element in a molecule

Question 4

what is the displayed/graphical formula

Answer 4

how atoms are arranged and all the bonds between them

Question 5

what is the shortened/structural formula

Answer 5

the minimum detail shows the C by C without functional groups

Question 6

what is the skeletal formula

Answer 6

bonds of C skeleton only but showing any functional groups in full

Question 7

What is an alkene functional group? what is the typical ending?

Answer 7

c=c
-ene

Question 8

what is an alcohol functional group? what is the typical ending?

Answer 8

-O-H
-ol

Question 9

what is an alkyl functional group? what is the typical ending?

Answer 9

-CH3
- yl

Question 10

what is an halogenoalkane functional group? what is the typical ending?

Answer 10

-F
-Cl
-Br
-I

Question 11

what is a carboxylic acid functional group? what is the typical ending?

Answer 11

-COOH (double bond between O and C)
-oic acid

Question 12

what is an aldehyde functional group? what is the typical ending?

Answer 12

(double bond between C and O, H bonded to C also) -al

Question 13

what is a ketone functional group? what is the typical ending?

Answer 13

R−C(=O)−R’
-one

Question 14

How are organic compounds covalent in character?

Answer 14

showing typical covalent properties, eg low mp and bp, non-electrolytes and molecular in structure

Question 15

what does it mean to be molecular in structure?

Answer 15

individual molecules not in structure

Question 16

what are organic compounds known as and how can they be prepared?

Answer 16

known as homologous series
can be prepared by same methods of preparation and the same functional group

Question 17

What are the basic rules for naming organic compounds? What’s this called?

Answer 17

Called Nomenclature
1. Identify the longest chain of carbons in the molecules
2. Identify the functional group
3. Identify the side chains

Question 18

What is the formula for methyl?

Answer 18

CH3

Question 19

What is the formula for ethyl?

Answer 19

CH3CH2

Question 20

What is the formula for propyl?

Answer 20

CH3CH2CH2

Question 21

What is the formula for butyl?

Answer 21

CH3CH2CH2CH2

Question 22

What do you do if different or less important functional groups are present when naming?

Answer 22

They are placed in alphabetical order
eg 3-ethy;-2-methyl pentane

Question 23

What do you do if there is more than 1 identical side-chain or functional group?

Answer 23

Use di- tri- or tetra- before that part of the name

Question 24

Draw 2-methyl pentan-1-ol (in book)

Question 25

Draw 1,2dichloro-3,3,4-triodopentane (in book)

Question 26

Draw methanoic acid (in book)

Question 27

Draw methyl propene (in book)

Question 28

why do smaller hydrocarbons have lower mp and bp? therefore? (states)

Answer 28

bc smaller surface area means that lower VDWs forces are possible and this means that the melting and boiling temp would be low therefore small hydrocarbons are gases at room temperature

Question 29

Why are hydrocarbons non-polar and what does this mean?

Answer 29

as the electronegativity of carbon and hydrogen are similar, this means only temporary dipole-dipoles have VDWs present between the molecules. This means the intermolecular forces are weak

Question 30

If the intermolecular forces are weak, why does the mp and bp increase in hydrocarbons as chain length increases?

Answer 30

bc VDWs forces act between the surfaces of molecules, the more surface there is in contact, the stronger the forces, which means more energy is needed to overcome the forces

Question 31

If mp and bp increases as chain length increases, why isn't this the case with branched hydrocarbons?

Answer 31

the more branches the isomer has, the less surface contact it has between molecules which means weaker VDWs so less energy needed to break the bonds between molecules so lower bp

Question 32

What is the effect of a polar group of alcohols? (OH)

Answer 32

adding a polar group increases the bp change in bp us caused by highly polar group resulting in molecules being able to bond between molecules

Question 33

describe the solubility of alcohols and carboxylic acids

Answer 33

the addition of a polar group increases the solubility of the molecule

Question 34

as chain length (of alcohols and carboxylic acids) increases... why?

Answer 34

as chain length increases, solubility decreases as the size of the hydrocarbon increases it exerts a large hydrophobic effect so the compound is no longer soluble

Question 35

why can't hydrocarbons like butane dissolve in water?

Answer 35

bc they only form VDWs interactions between molecules and are not able to form significant attraction with the polar water molecules

Question 36

What is chain isomerism Give an example

Answer 36

different arrangements of carbon skeleton C4H10 has two structural isomers: Butane and 2-methyl propane

Question 37

What is position isomerism? Give an example

Answer 37

same carbon skeleton and same functional group but on different carbons Butan-1-ol and Butan-2-ol

Question 38

What is functional group isomerism? Give an example

Answer 38

same molecular formula but different functional group C4H8O has 2 different possible functional groups, an aldehyde of a ketone

Question 39

What are some practical methods to test for physical properties?

Answer 39

Distillation Reflux Separating flannel

Question 40

What is heating by reflux?

Answer 40

a reaction mixture is heated to rate of reaction and a condenser is placed above the reaction mixture so any evaporated reactants or products are condensed and returned to the reaction mixture.

Question 41

Draw a the apparatus for heating by reflux. (book)

Question 42

Describe the process of a separating flannel

Answer 42

used to separate 2 immiscible liquids, the mixture is allowed to settle and then lower layers can be removed using the tap, leaving the less dense layer in the funnel (water denser)

Question 43

When does sterioisomerism happen?

Answer 43

occurs in molecules having a c=c bond which can rotate

Question 44

When drawing sterioisomers, what do you have to make sure of?

Answer 44

atom w the highest atomic no. takes priority eg H

Question 45

What is a Z isomer?

Answer 45

if both highest priority groups are on the adjacent side of the double bond

Question 46

Draw 1-bromo-2-chloroprop-1-ene normal and its isomers

Question 47

why are the physical properties of E-Z isomers different?

Answer 47

bc different postions of groups and chains affects the shape, dipole and intermolecular forces

Question 48

The chemical properties of E-Z isomers are usually similar, what is the exception?

Answer 48

if two of the groups are important, the chemical properties will be different

Question 49

Which has a lower mp and stability between E-Z? Which is more soluble and has a greater heat of combustion? Which one is more reactive? why is it more reactive?

Answer 49

Z isomers Z isomers Z isomers priority groups are on the same side which creates repulsion making the molecules more strained and reactive

Question 50

state why chloroethene monomer does not exhibit E-Z isomerism

Answer 50

2 hydrogen atoms on 1 of the carbons

Question 51

what do you have to remember about chain length on melting and boiling temperatures?

Answer 51

many branches - little surface area contact and so lower mp and bp straight chain - more surface area contact so higher mp and bp