alcohols

Question 1

description of an aldehyde

Answer 1

functional group CHO
carbonyl bonded to at least one H atom
name ends in …al

Question 2

description of a ketone

Answer 2

functional group is CO
carbonyl bonded to two C atoms
name ends in ….one

Question 3

description of a carboxylic acid

Answer 3

functional group is COOH
carbonyl bonded to an OH group
name ends in …oic acid

Question 4

alcohol classification

Answer 4

primary alcohol- C bonded to OH is bonded to one other C
secondary alcohol - C bonded to OH is bonded to two other C
tertiary alcohol - C bonded to OH is bonded to three other C

Question 5

observation for alcohol oxidation

Answer 5

orange to green
acidified K2Cr2O7 is used as an oxidising agent

Question 6

primary alcohol to aldehyde

Answer 6

reagent - acidified K2Cr2O7
conditions - heat under distillation
CH3CH2OH + [O] -> CH3CHO + H2O

Question 7

aldehyde to carboxylic acid

Answer 7

reagent - acidified K2Cr2O7
conditions - heat under reflux
CH3CHO + [O] -> CH3COOH

Question 8

primary alcohol to carboxylic acid

Answer 8

reagent - acidified K2Cr2O7
conditions - heat under reflux, excess oxidising agent
CH3CH2OH + 2[O] -> CH3COOH + H2O

Question 9

oxidation of secondary alcohols

Answer 9

reagent - acidified K2Cr2O7
conditions - heat under reflux/distillation
CH3CH(OH)CH3 + [O]-> CH3COCH3 + H2O

Question 10

features of a condenser

Answer 10

open at both ends
cold water flows around outside

Question 11

purpose of a condenser

Answer 11

cools hot vapour and condenses to liquid

Question 12

purpose of anti bumping granules

Answer 12

prevent the formation of large bubbles

Question 13

why is reflux used to oxidise a primary alcohol to a carboxylic acid

Answer 13

reflux doesnt allow any reactant vapour to escape

Question 14

model answer
describe when a reaction mixture is refluxed

Answer 14

-ethanol and acidified potassium dichromate (vI) are heated to boiling point for a prolonged time
-ethanal vapour is formed which escapes from the liquid mixture and is then condensed back into liquid and returned to the reaction mixture
-any ethanol and ethanal that initially evaporates can then be oxidised

Question 15

what happens to an aldehyde as it is produced during distillation

Answer 15

the aldehyde forms as a vapour and escapes from the reaction mixture into the condenser

Question 16

tollens reagent - [Ag(NH3)2]+

Answer 16

used to test aldehydes
silver mirror forms
when no aldehyde no visible change

Question 17

fehlings solution - Contains Cu2+

Answer 17

used to test for aldehydes
forms brick-red precipitate

Question 18

test for carboxylic acids -

Answer 18

Na2CO3 forms effervescence

Question 19

Producing ethanol from crude oil
Hydration

Answer 19

Hydration
Ch2=ch2 + h2o -> ch3ch2oh
Conditions - conc h3po4 catalyst, steam , 450c temp, 50-100atm pressure

Question 20

Producing ethanol from fermentation

Answer 20

C6h12o6 -> 2ch3ch2oh + 2co2
Conditions - yeast enzymes (zymase) , 35c temp , no oxygen

Question 21

Advantages of hydration of ethene

Answer 21

Large scale production method
High purity product made
High rate of reaction
Continuous production method

Question 22

Disadvantages of hydration of ethene

Answer 22

High temp and pressure which increases cost
Expensive and high tech equipment needed

Question 23

Fermentation advantages

Answer 23

Uses renewable resources
Low tech suitable for developing countries and little expensive equipment needed

Question 24

Fermentation disadvantages

Answer 24

Slower rate of reaction
Impure product made that still needs distilling

Question 25

Biofuel advantages

Answer 25

Considered to be carbon neutral
Come from renewable raw materials
Provide employment for farmers to grow the crops

Question 26

Biofuel disadvantages

Answer 26

Many other carbon costs meaning they aren’t carbon neutral as carbon produced through other processes eg transportation
Supply of biofuels dependant on crop harvest so it’s not reliable
Biofuel cannot be made on a scale to meet global demands for fuels