17.3

Question 1

what is the group for carboxylic acids

Answer 1

COOH

Question 2

name the compound CH3CH2COOH

Answer 2

propanoic acid

Question 3

name the compound HOOCCOOH

Answer 3

ethanedioic acid

Question 4

what is the structure of formic acid

Answer 4

HCOOH

Question 5

what is the structure of acetic acid

Answer 5

CH3COOH

Question 6

what is the structure of oxalic acid

Answer 6

HOOCCOOH

Question 7

what is the structure of benzoic acid

Answer 7

C6H5COOH

Question 8

how many polar bonds are there in a carboxylic acid

Answer 8

3 (all of them)

Question 9

what forms a carboxylate ion (COO-)

Answer 9

loss of a hydrogen from a carboxylic acid

Question 10

what are the physical characteristics of carboxylic acids

Answer 10

distinctive smells and sour tastes

Question 11

explain why carboxylic acids have high melting and boiling points

Answer 11

the 3 polar bonds mean that they have strong intermolecular forces (hydrogen bonding) which require large amounts of energy to overcome

Question 12

what is the trend in melting and boiling points as chain length of carboxylic acids increases

Answer 12

melting and boiling points increase as chain length increases because London forces between non-polar hydrocarbon chains increase which require more energy to overcome

Question 13

how do dimers form in carboxylic acids

Answer 13

in the absence of water hydrogen bonds form between carboxylic acid groups on shorter chain carboxylic acids

Question 14

what is the trend between solubility and chain length of carboxylic acids and why

Answer 14

solubility decreases as chain length increases because shorter chain carboxylic acids can form hydrogen bonds with water molecules whereas longer chain carboxylic acids can’t

Question 15

what is formed when carboxylic acids are reduced

Answer 15

primary alcohols

Question 16

what is formed when carboxylic acids in a neutralization reaction

Answer 16

carboxylate salt

Question 17

what is formed when carboxylic acids in a halogenation reaction

Answer 17

acyl chloride

Question 18

what is formed when carboxylic acids in an esterification reactions

Answer 18

ester

Question 19

how are carboxylic acids formed from oxidation

Answer 19

oxidation of primary alcohols or aldehydes using acidified potassium dichromate (VI) and heated under reflux
then fractionally distil the product to obtain a pure sample

Question 20

what does [O] represent in an equation for the formation of a carboxylic acid

Answer 20

the oxygen supplied by acidified potassium dichromate (VI)

Question 21

how are carboxylic acids formed from hydrolysis

Answer 21

nitriles under go hydrolysis under reflux with dilute acid or aqueous alkali which breaks the CN triple bond and produces a carboxylic acid and ammonia or an ammonium ion

Question 22

what occurs in the acidic hydrolysis of nitriles

Answer 22

heated under reflux with a dilute acid producing a carboxylic acid and ammonium _______ (e.g. HCl acid gives ammonium chloride)

Question 23

what occurs in the alkaline hydrolysis of nitriles and how can you produce a carboxylic acid from this reaction

Answer 23

heated under reflux with sodium hydroxide solution sodium salt and ammonia gas are produced
the products must then be acidified with a strong acid to create a carboxylic acid

Question 24

why can carboxylic acids not be reduced to aldehydes

Answer 24

because aldehydes are more easily reduced than carboxylic acids so any aldehyde produced will be immediately reduced to a primary alcohol

Question 25

what are the conditions and reducing agent for the reduction of carboxylic acids

Answer 25

lithium tertahydridoaluminate in a solvent of dry ether

Question 26

what is used in neutralizing carboxylic acids

Answer 26

aqueous alkali

Question 27

what is the reagent and conditions for the halogenation of carboxylic acids

Answer 27

phosphorus(V) chloride in anhydrous conditions

Question 28

why must anhydrous conditions be used for the halogenation of carboxylic acids

Answer 28

because the acyl chloride product and reagent (phosphorus(V) chloride) react with water

Question 29

what is produced and what can be observed in the halogenation of carboxylic acids

Answer 29

phosphorus trichloride oxide and acyl chloride is in solution and must be fractionally distilled to get pure products misty fumes produced from hydrogen chloride gas given off

Question 30

what are the uses of esters in industry

Answer 30

solvents polymers (polyesters)

Question 31

what are the reagents for the esterification of carboxylic acids

Answer 31

alcohol and an acid catalyst (concentrated sulfuric acid)

Question 32

what is the general formula for acyl chlorides

Answer 32

RCOCl

Question 33

how are acyl chlorides produced form carboxylic acids

Answer 33

the OH group in COOH is replaced by Cl

Question 34

how does the structure of acyl chlorides effect how it reacts

Answer 34

the central carbon atom is attached to 2 electronegative atoms so it becomes electron deficient (&+) therefor it will readily react with nucleophiles (often molecules containing an O or N)

Question 35

how do acyl chlorides react with water

Answer 35

react vigorously with cold water producing a carboxylic acid and hydrogen chloride gas which can be seen as misty fumes given off

Question 36

how do acyl chlorides react with alcohols

Answer 36

react readily and produce a carboxylic acid and hydrogen chloride gas which can be seen as misty fumes given off

Question 37

what is the first stage of the reaction between acyl chloride and concentrated ammonia solution

Answer 37

an amide and hydrogen chloride gas is produced which can be seen as misty fumes given off

Question 38

what is the second stage of the reaction between acyl chloride and concentrated ammonia solution

Answer 38

the amide acts as a base and hydrogen chloride is an acidic gas therefor they react together to produce ammonium chloride

Question 39

what is the general formula for primary amines

Answer 39

RNH2

Question 40

what is formed in the reaction between a primary amine and acyl chloride

Answer 40

N-substituted amide

Question 41

what does N-substituted amide mean in a molecule

Answer 41

shows that there is a alkyl group attached to the N not the C

Question 42

what is the general formula for secondary amines

Answer 42

R2NH

Question 43

what is formed in the reaction between a secondary amine and acyl chloride

Answer 43

two substituted amide N-N-dimethylethanamide

Question 44

what is the general formula for tertiary amines

Answer 44

R3N

Question 45

why do acyl chlorides not react with tertiary amines

Answer 45

because there is no H atom to react with Cl to form hydrogen chloride

Question 46

what are the physical properties of esters

Answer 46

colourless liquids low mp & bp insoluble in water

Question 47

why are esters insoluble

Answer 47

all of the hydrogen atoms are attached to carbon atoms therefor hydrogen bonding cannot occur

Question 48

what are esters often used in

Answer 48

perfumes food flavorings solvents anesthetic biofuels

Question 49

define hydrolysis

Answer 49

the breaking of a compound by water

Question 50

describe the hydrolysis of esters in acidic conditions

Answer 50

warm with water and sulfuric acid (acts as a catalyst) to form a carboxylic acid and an alcohol

Question 51

describe the hydrolysis of esters in alkaline solution

Answer 51

heated under reflux with sodium hydroxide to form a carboxylate salt and an alcohol

Question 52

how can a carboxylate salt produced from the alkaline hydrolysis of esters be converted to a carboxylic acid

Answer 52

add dilute acid

Question 53

define condensation polymerisation

Answer 53

the formation of a polymer by the reaction of two different monomers in which a small molecule is also formed (usually water)

Question 54

what is the difference between addition and condensation polymerisation

Answer 54

condensation polymerisation involves 2 different monomers and a small molecule is produced (usually water)

Question 55

what is a diol

Answer 55

molecule has a hydroxyl group on each end