Ch. 6 Classes of Organic Compounds

Question 1

What is the shape of carbon with four single bonds

Answer 1

tetrahedral

Question 2

What is the shape of carbon with one double and two singles

Answer 2

planar

Question 3

What is the shape of carbon with two doubles, or one triple and one single

Answer 3

linear

Question 4

What are the two main categories of hydrocarbons

Answer 4

aromatic

aliphatic

Question 5

Are hydrocarbons polar or nonpolar and why

Answer 5

• Hydrocarbons are non- polar

o Due to carbon & hydrogen having similar electronegativity + relatively symmetrical shape of most hydrocarbons

Question 6

Why do hydrocarbons have weak intermolecular bonding

Answer 6

• only intermolecular force of attraction b/w adjacent molecules= dispersion forces
  o Weak intermolecular force resulting from momentary dipoles

Question 7

when does the strength of dispersion forces increase for hydrocarbons

Answer 7

1. Close together (depends on molecule shape)

Larger as there are more region of charge to attract one another

Question 8

difference between cis and trans

Answer 8

o Cis= same side

o Trans= opposite sides

Question 9

what are the chemical reactions of alkynes

Answer 9

combustion and addition

Question 10

What are the stem names for first 6 carbons

Answer 10

meth
eth
prop
but
pent
hex

Question 11

What is the suffix, and functional group for alcohol

Answer 11

• ol

- OH

Question 12

What is the suffix, and functional group for aldehyde

Answer 12

• al

- C=o, h

Question 13

What is the suffix, and functional group for ketone

Answer 13

• one

- C=O

Question 14

What is the suffix, and functional group for carboxylic acid

Answer 14

• oic acid

- C=O,-OH

Question 15

What is the suffix, and functional group for ester

Answer 15

• alkyl oate

- C=O, -O

Question 16

What is the suffix, and functional group for amine

Answer 16

• amine

- NH2

Question 17

What is the suffix, and functional group for amide

Answer 17

• amide

- C=O, NH2

Question 18

why are alcohols polar

Answer 18

• Presence of electronegative oxygen atom means CO and OH bonds are very polar
  o // hydrogen bonding occurs in alcohol

Question 19

What are the three types of alcohol and the differences

Answer 19

1. Primary- one carbon atom bonded to carbon atom with OH
2. Secondary- two carbon atoms bonded to carbon atom with OH
3. Tertiary- three carbon atoms bonded to carbon atom with OH

Question 20

are secondary, tertiary or primary alcohols stronger oxidised

Answer 20

o Primary more readily oxidized by strong oxidizing agent than secondary, and tertiary not oxidized

Question 21

What are th four processes in preparing alcohol

Answer 21

1. fermentation
2. hydrogenation
3. hydrolysis of alkenes
4. reduction of ketone/aldehyde

Question 22

What do ketone and aldehydes reduce to

Answer 22

• Aldehyde primary

- Ketone secondary

Question 23

What five reactions can alcohols participate in

Answer 23

combustion

dehydration

reaction with sodium (hydrogen made)

oxidation

Esterifaction

Question 24

explain oxidation of alchols

Answer 24

• Alcohols readily undergo oxidation with strong oxidizing agents such as acidified permanganate or dichromate
• Hydrogen on left, water on right
  a. Primary alcohols
• Form aldehydes, which then further oxidized to carboxylic acids
  R-CH2OH R-CHO R-COOH
• E.g. ethanol ethanal ethanoic acid
• Removing aldehyde as soon as its formed= wont be converted to carboxylic acid

b. Secondary alcohols
- Form ketones which cannot be further oxidized
RCHOHR’ RCOR’

c. Tertiary alcohols
- Resistant to oxidation

Question 25

what colour does dichromate change to when oxidised

Answer 25

orange > green

Question 26

are ketones and aldehydes polar or non polar and why

Answer 26

- Oxygen more electronegative than carbon // tendency to attract electrons in carbon-oxygen bond= bond highly polar o Because of this polarity, dipole-dipole forces exist between molecules

Question 27

What are the four properties of carboxylic acids

Answer 27

monoprotic strength polar solubillity

Question 28

explain carboxylic acids monoprotic nature

Answer 28

o As the only H atom that can react with a base is the one on the –COOH group - other hydrogens non polar bonded

Question 29

explain carboxylic acids strength and why

Answer 29

- strength increased by substituting a highly electronegative atom (such as a halogen) onto the chain o Due to: strong electron attracting power of substituent weakens oxygen hydrogen bond in the –OH group + makes easier to form H+ ions

Question 30

explain carboxylic acids polarity

Answer 30

o The presence of –OH and –C=O groups makes carboxyl polar | ♣ So they can form strong hydrogen bonds

Question 31

explain carboxylic acids solubility

Answer 31

o Smaller carboxylic acids= soluble in water as strong polar carboxyl group is hydrophilic (loves water) + // able to hydrogen bond to water o However, as the size of the hydrophobic (water hate) carbon chain increases, solubility decreases

Question 32

what are the four reactions carboxylic acids can participate in

Answer 32

1. reaction with reactive metals 2. reaction with base (neutralisation) 3. reaction with carbonate 4. esterifaction

Question 33

explain carboxylic acid reaction with base

Answer 33

- Hydrogen in –COOH group bonds with OH in base= water, remaining molecule= negative, metal from base= ion

Question 34

explain carboxylic acid reaction with carbonate

Answer 34

- Hydrogen in –COOH group bonds with oxygen in carbonate= water, remaining oxygen and carbon from carbonate=CO2, remaining molecule=negative, metal from carbonate= ion

Question 35

why is production of esters condensation

Answer 35

water produced

Question 36

how are esters synthesised

Answer 36

alcohol + carboxylic acid

Question 37

naming esters

Answer 37

1. The first part of the name is the alkyl group, comes from the alcohol from which the ester is formed 2. The second part comes from the carboxylic acid used in the ester formation, the end of the acid name is changed from –oic acid to –oate

Question 38

What are the two reactions of esters

Answer 38

- hydrolysis | - saponification

Question 39

explain hydrolysis of esters

Answer 39

- reverses to form alcohol and carboxylic acid | - happens under acidic or alkaline conditions

Question 40

when are amide formed

Answer 40

amine + carboxylic acid

Question 41

what is the functional group for amines

Answer 41

nh2

Question 42

what are the three types of amines and why

Answer 42

o Primary amine= one alkyl group attached to the nitrogen o Secondary amine= two alkyl groups attached to nitrogen o Tertiary amine= three alkyl groups attached to nitrogen

Question 43

is the nh2 group polar

Answer 43

yes

Question 44

why are hydrogen bonds in amines weaker than alcohol's

Answer 44

- itrogen= less electronegative than O, hydrogen bonds formed by amines are weaker than those formed by alcohols o = lower b.p. than similar alcohols

Question 45

what are the two reactions of primary amines

Answer 45

- reaction with inorganic acids | - reaction with organic acids (amine + carboxylic= amide)

Question 46

how are primary amides and secondary amides produces

Answer 46

- Primary produced in two steps 1. The carboxylic acid is converted to an ammonium salt using ammonium carbonate (typical acid-carbonate reaction) 2. The resultant mixture is then heated to dehydrate the ammonium salt, producing the amide - Secondary amides are produced by the reaction of a carboxylic acid and primary amine