alchohols

Question 1

what is the general formular for alcohols

Answer 1

CnH2n+1OH

Question 2

how do you name alcohols

Answer 2

the suffix is -ol with the number of placement before
the prefix is hydroxyl with the number before

Question 3

what is the boiling points of alcohols

Answer 3

alcohols have relatively low volatility and high boiling points due to their ability to form hydrogen bonding between alcohol molecules

Question 4

are alcohols soluble in water

Answer 4

smaller alcohols will dissolve in water as they can form hydrogen bonding to water molecules

Question 5

what are the different types of alcohols

Answer 5

primary- two hydrogens
secondary-one hydrogen
tertiary-no hydrogens

Question 6

what is the reagent we use to oxidise alcohols

Answer 6

K2Cr2O7 potassium dichromate

Question 7

what is the reaction reagent and conditions of partial oxidation or primary alcohols

Answer 7

reaction- primary alcohol -> aldehyde

reagent: potassium dichromate solution and dilute sulphuric acid

conditions- warm gently and distil ou tth aldehyde as it forms

Question 8

what is a primary alcohol

Answer 8

primary alcohols are alcohols where 1 carbon is attached to the carbon adjoining the oxygen

Question 9

what is a secondary alcohol

Answer 9

secondary alcohols are alcohols where 2 carbons are attached to the carbon adjoining the oxygen

Question 10

what is a tertiary alcohol

Answer 10

tertiary alcohols are alcohols where 3 carbon are attached to the carbon adjoining the oxygen

Question 11

what is an aldehydes functional group

Answer 11

C double bond O and one hydrogenand one alkly group

Question 12

what are the observation you see when the partial oxidisation of alcohols to aldehydes reaction takes place

Answer 12

the solution goes from orange to green due to the dichromate ion reducing to copper 3+ ion

Question 13

what is the apparatus needed for partial oxidation of primary alcohols to an aldehyde

Answer 13

immediate distillation

Question 14

what is distillation used for

Answer 14

used as a separation technique to separate an organic product from its reacting mixture. in order to maximise yield collected

Question 15

why do we have to immediately distillate the aldehyde out in the oxidation of primary alcohols to aldehydes and how does it work

Answer 15

as soon as the aldehyde forms it is distilled out of the oxidising mixture to prevent further oxidation it works because aldehydes have lower boiling points then alcohols
if the aldehyde isn’t distilled away then it will oxidise again to form a carboxylic acid

Question 16

what is the reaction, reagent and conditions for the full oxidation of a primary alcohol

Answer 16

reaction- primary alcohol -> carboxylic acid

reagent- potassium dichromate (VI) solution and dilute sulfuric acid

conditions- use an excess of dichromate, and heat under reflux (distil off product after reaction has finished)

Question 17

what is the functional group of a carboxylic acid

Answer 17

O double bond C bond OH

Question 18

what is the observation in the full oxidation of a primary alcohol

Answer 18

orange to green

Question 19

why does the full oxidation of primary alcohols have to be done under reflux

Answer 19

so any aldehyde that evaporates away returns to be fully oxidised into a carboxylic acid

Question 20

what is reflux and what is it used for

Answer 20

reflux is used when heating organic reaction mixtures for long periods, the condenser prevents organic vapours from escaping by condensing them back into a liquid

Question 21

why do we put water into the bottom of a condenser

Answer 21

works against gravity which produces a more efficient cooling and prevents back flow

Question 22

what should you never do to the condenser in a reflux

Answer 22

seal the end as it could cause a build up in gas and explode

Question 23

what are ani bumping granules and what are they for

Answer 23

anti bumping granules are added to the flask in both distillation and reflux to prevent vigorous, uneven boiling by making small bubbles form instead of large bubbles

Question 24

what is the reaction and reagent and conditions for secondary alcohols

Answer 24

the reaction is secondary alcohols to ketone

the reagent is potassium dichromate (VI) solution and dilute sulfuric acid

the conditions are heat under reflux

Question 25

what is the functional group of a ketone

Answer 25

function group C double bond O the same as an aldehyde however it comes from secondary alcohols and so has one hydrogen and one alkyl group

Question 25

what are the observation for the oxidization of secondary alcohols

Answer 25

orange to green

Question 26

can ketone be further oxidised

Answer 26

not in those conditions

Question 27

why cant tertiary alcohols be oxidised

Answer 27

they cant be oxidised by potassium dichromate this si because there is no hydrogen atom bonded to the carbon with the -OH group

Question 28

what are the two tests for aldehydes

Answer 28

tollens regent Fehling's solution

Question 29

what is tollens reagent and how do you make it

Answer 29

tollens reagent is a colourless solution containing Ag+ ions to make it put 2cm3 of silver nitrate into a test tube. add a few drops of NAOH to form a brown precipitate then add dilute ammonia to dissolve the precipitate

Question 30

what are the conditions for the tollens reagent test

Answer 30

heating gently

Question 31

what is the observation of the tollens reagent test

Answer 31

a silver mirror forms due to the aldehydes

Question 32

what is the reaction that takes place in the tollens reagent test

Answer 32

aldehydes only are oxidised by tollens reagent into a carboxylic acid. the silver ions are reduced to silver atoms.

Question 33

what do we use tollens reagent or Fehling's solution to distinguish aldehydes

Answer 33

to distinguish between aldehydes and ketones as ketones cant further oxidises but aldehydes can to a carboxylic acid

Question 34

what is Fehling's solution and how is it made

Answer 34

Fehling's solution is a blue solution of copper ions to make it add 2cm3 of Fehling's solution and warm it in unknown solution in a water bath

Question 35

what is the observation in the test for aldehydes with Fehling's solution

Answer 35

the clue copper 2+ ions in the solution change and form a red precipitate

Question 36

what is the reaction that takes place in the Fehling's test for aldehydes

Answer 36

aldehydes only are oxidised by Fehling's solution into a carboxylic acid. The copper ions are reduced to copper oxide

Question 37

how do you test for a carboxylic acid

Answer 37

the presence of a carboxylic acid can be tested by addition of sodium carbonate. it will fizz and produce carbon dioxide

Question 38

what is the reagent for the reaction of alcohol to an alkene and what was the reagent purpose

Answer 38

concentrated sulfuric or phosphoric acid and acts as a dehydrating agent

Question 39

what is the type of mechanism that occurs in the dehydration of alcohols to an alkene

Answer 39

elimination

Question 40

what happens in a dehydration reaction

Answer 40

the removal of a water molecule from a molecule

Question 41

how com some secondary and tertiary alcohols can form different alkene in a dehydration reaction

Answer 41

they can form on wither side of the carbocation if there is a hydrogen present on the neighbouring carbon atom

Question 42

at are the two methods to form ana alcohol

Answer 42

fermentation and hydration

Question 43

what is the reaction for fermentation and what are the conditions needed for it

Answer 43

glucose to ethanol and carbon dioxide and the conditions are -yeast -anaerobic conditions -30-40 degrees Celsius

Question 44

why is it important to stay at the optimum temperature in fermentation

Answer 44

if it is to low the reaction is really slow and if it is two high the enzymes denature

Question 45

why is fermentation done is anaerobic conditions

Answer 45

fermentation has to be done in the absence of air because the presence of air can cause extra reactions to occur. and may oxidise the ethanol producing ethanoic acid

Question 46

what are the advantages of producing ethanol through fermentation

Answer 46

-sugar is a renewable resource -production uses cheap equipment

Question 47

what are the disadvantages of fermentation to make alcohol

Answer 47

-batch process which is slow and gives high production costs -ethanol made is not pure and needs purifying by fractional distillation (costly) -depletes land used for growing food crops

Question 48

what is the reagent and type of reaction for the production of ethanol through hydration

Answer 48

the regent is ethene from cracking of fractions from distilled crude oil the mechanism is addition

Question 49

what are the essential conditions for the production of ethanol from ethene

Answer 49

- high temperature 300 degrees -high pressure 70 atm -strong acidic catalyst of concentrated phosphoric acid catalyst

Question 50

what are the advantages of producing alcohol through the hydration of Ethene to ethanol

Answer 50

-faster reaction -purer product -continuous process (which means cheaper manpower) -no waste such as carbon dioxide

Question 51

what are the disadvantages of producing ethanol from ethene through hydration

Answer 51

-high technology equipment needed which is expensive -ethene is non renewable resource -high energy costs for pumping to produce high pressures and high temperatures -reversable reaction so low yeild

Question 52

what does carbon neutral mean

Answer 52

an activity that has no net annual carbon emissions to the atmosphere

Question 53

what is a biofuel

Answer 53

renewable fuels derived from recently living biological materials such as plants

Question 54

when is ethanol considered a biofuel

Answer 54

wen it is produced through fermentation

Question 55

how ethanol proved to be carbon neutral

Answer 55

6 moles for carbon dioxide has to be absorbed by a plant during photosynthesis to make one mole of glucose one moles of glucose is fermented 2 moles of carbon dioxide is released when the ethanol is being burnt the two moles of ethanol from the ne mole of glucose releases 4 moles of carbon dioxide so in total 6 moles absorbed and 6 moles released

Question 56

why is ethanol as a biofuel actually not carbon neutral

Answer 56

the energy needed to grow and produce the plant as well as fractional distil the ethanol may not come from a renewable source which would make it not carbon neutral