organics II 5.4

Question 1

what are alcohols?

Answer 1

organic molecules containing an -OH functional group

Question 2

what is the formula of methanol?

Answer 2

CH3OH

Question 3

what is the formula of ethanol?

Answer 3

C2H5OH

Question 4

what is the formula of propanol?

Answer 4

C3H7OH

Question 5

what is the formula of butanol?

Answer 5

C4H9OH

Question 6

why is a number sometimes involved in the name of the alcohol?

Answer 6

as -Oh can be attached in the middle of the carbon chain instead of the end

Question 7

industrial ethanol manufacture
hydration of ethene:

Answer 7

ethene (C2H4) gas is mixed with steam (H2O)

Question 8

industrial ethanol manufacture
hydration of ethene - advantages:

Answer 8

makes pure ethanol
can run continuously

Question 9

industrial ethanol manufacture
hydration of ethene - conditions needed:

Answer 9

300 degrees
65 atm pressure
phosphoric acid (H3PO4) catalsyt

Question 10

industrial ethanol manufacture
hydration of ethene disadvantages:

Answer 10

conditions require lots of energy
non-renewable raw material used (crude oil)

Question 11

industrial ethanol manufacture
fermentation of glucose:

Answer 11

glucose (C6H12O6) is fermented microbiologically

Question 12

industrial ethanol manufacture
fermentation of glucose - conditions needed:

Answer 12

yeast (provides enzymes)
30 degrees (optimum temperature for enzymes)
anaerobic (no oxygen) prevents oxidation

Question 13

industrial ethanol manufacture
fermentation of glucose advantages:

Answer 13

renewable raw material used (sugar cane)
conditions not energy-intensive

Question 14

industrial ethanol manufacture
fermentation of glucose - disadvantage:

Answer 14

makes impure ethanol
must be done in individual batches

Question 15

oxidation
ethanol combustion:

Answer 15

ethanol tends to completely combust because of the oxygen atom in the -OH group
resulting in a non-luminous blue flame

C2H5OH + 3O2 > 2CO2 + 2H2O

Question 16

oxidation
ethanol microbial oxidation:

Answer 16

many micro organisms such as bacteria and fungi use oxygen in the air to oxidise ethanol into ethanoic acid

can happen aerobically

C2H5OH + 2O > CH3COOH + H2O

Question 17

oxidation
ethanol chemical oxidation:

Answer 17

heat ethanol with potassium dichromate (VI) and dilute sulphuric acid
this forms ethnic acids
C2H5OH + 2O > CH3COOH + H2O

the orange dichromate ions are turned into a green chromium ions
meaning reaction always has colour change

Question 18

what are carboxylic acids?

Answer 18

organic molecules containing an -COOH functional group

Question 19

what is the formula for methanoic acid?

Answer 19

HCOOH

Question 20

what is the formula for ethanoic acid?

Answer 20

CH3COOH

Question 21

what is the formula for propanoic acid?

Answer 21

C2H5COOH

Question 22

what is the formula for butanoic acid?

Answer 22

C3H7COOH

Question 23

what is vinegar?

Answer 23

an aqueous solution of ethanoic acid

Question 24

how do you form vinegar?

Answer 24

when ethanol undergoes microbial oxidation
C2H5OH + 2O > CH3COOH +H2O

vinegar has a very sour and acrid taste because of the acidity of ethanoic acid

Question 25

how can carboxylic acids act as acids?

Answer 25

carboxylic acids can donate H+ to from a salt
as it looses its H and becomes negatively charged
its name changes from ethanoic acid to ethanoate

Question 26

what would you observe in carboxylic acid + metal > salt + hydrogen reaction?

Answer 26

effervescence
- due to hydrogen gas being produced
solid disappearing
- due to metal being used up in reaction

methanoic acid + sodium > sodium methanoate + hydrogen

Question 27

what would you observe in carboxylic acid + metal carbonate > salt + water + carbon dioxide reaction?

Answer 27

effervescence
- due to carbon dioxide being produced
solid disappears
- due to metal carbonate being used up in reaction

methanoic acid + sodium carbonate > sodium methanoate + water + carbon dioxide

Question 28

what are esters?

Answer 28

a family of organic molecules which form when a carboxylic acid and an alcohol join together by losing an H2O molecule

Question 29

what is the ester functional group?

Answer 29

-COO-

Question 30

what is the ester reaction?

Answer 30

carboxylic acid + alcohol > ester + water

Question 31

what is the ester that is formed called?

Answer 31

for example
ethyl ethanoate

Question 32

what type of reaction is carboxylic acid + alcohol > ester + water?

Answer 32

condensation as it produces water vapour
esterification as it makes an ester

Question 33

how do you produce/ make an ester?

Answer 33

1. mix the carboxylic acid and alcohol together
2. add a few drop of concentrated sulphuric acid - this acts as a catalyst for the reaction
3. warm it for a while
4. tip the mixture into sodium carbonate solution, this neutralises the sulphuric acid catalyst, which is otherwise corrosive
   the reaction produces CO2 so wait until the fizzing has stopped

Question 34

what is the use of esters?

Answer 34

volatile compounds with distinctive smells
making them suitable for use in food flavourings and perfumes

Question 35

what are polyesters?

Answer 35

a polymer made up off lots of molecules joined together in a chain by ester groups

Question 36

what two types of monomers do you need to make a polyester?

Answer 36

dicarboxylic acid (that has -COOH- at both ends)
diol (has -OH at both ends)

Question 37

what type of polymerisation is this?

Answer 37

condensation polymerisation

Question 38

why is making polyesters condensation polymerisation?

Answer 38

as each time a monomer joins the end of the chain a H2O molecule is lost

Question 39

what are biopolyesters?

Answer 39

some polyesters are biodegradable, which means microbes such as bacteria and fungi can use enzymes to break down the polymer into its monomers and use them as an energy supply

this is a good thing as it reduces landfill and incineration need to dispose of polyesters