OXIDATION OF FOOD

Question 1

When chemicals in food are exposed to oxygen in air

Answer 1

chemical composition changes and they begin breaking down

Question 2

animal and plant tissues contian

Answer 2

antioxidants molecules to prevent breaking down by oxygen exposure

slow down rate of discolour/break down

Question 3

food left unattended

Answer 3

lose nutritional value and begin to break down and discolour

Question 4

alcohol functional group

Answer 4

OH

Question 5

what kind of series is alochols

Answer 5

homologous

CnH2n+OH

Question 6

names end in

Answer 6

-ol

Question 7

Types of alcohols

Answer 7

Primary
Secondary
Tertiary

Question 8

Primary alcohols

Answer 8

hydroxyl group on a C with at least 2 H

AT END

Question 9

Secondary alcohols

Answer 9

Hydroxyl OH attached to Carbon with at least 1 Hydrogen

Somewhere in middle of carbon chain

Question 10

Tertiary alcohols

Answer 10

Hydroxyl OH attached to a carbo with no H attached

on branch with carbon that is attached to other carbon branch so no H

Question 11

Oxidation of alcohol

Answer 11

Using oxidation agent

Question 12

Oxidisation agent examples

Answer 12

acidified potassium dichromate

acidified potassium permanganate

hot copper (II) oxide (black solid)

Benedicts reagent

Tollens reagent (silver-mirror)

Question 13

Oxidation of primary alcohol

Answer 13

Forms 2 products in 2 stage reaction

Oxygen Hydrogen ratio increases so O added or H removed

1. Loses 2 H to form aldehyde
2. Oxygen added to aldehyde to form carboxylic acid

Question 14

oxidation of propan-1-ol

Answer 14

PROPANAL + WATER

Question 15

oxidisation primary alcohol summary

Answer 15

Primary alcohol
Aldehyde
Carboxylic Acid

Question 16

Oxidation of secondary alcohol

Answer 16

only once

form ketones (alkanones)

Question 17

ketone

Answer 17

-one

carbonyl group never at end (c double bond O)

lose H gain double bond from secondary alcohol

propanone and butanone not need numbers as always number 2

Question 18

Tertiary alcohol oxidation

Answer 18

Not readily oxidised

Question 19

Many common flavours for cooking formed from

Answer 19

aldehydes and ketones

Question 20

group in both ketones and aldehydes

Answer 20

corbonyl group

Question 21

Aldehyde

Answer 21

Alkanal

Have carbonyl group at end of carbon chain

end in -al

when naming carbonyl number not needed as always 1

Question 22

carbonyl group

Answer 22

C double bond O

Question 23

how to tell ketone and aldehyde apart

Answer 23

using oxidising agent act different

Question 24

acidified potassium dichromate colour change

Answer 24

orange to green

Question 25

fehling's soluton colour chnage

Answer 25

blue to brick red preticipate

Question 26

Tollen's reagent colour change

Answer 26

Clear to silver mirror participate

Question 27

carboxylic acid

Answer 27

contain carboxyl group (-COOH)) always on C1 -oic acid

Question 28

Reactions with carboxylic acids

Answer 28

Undergo reduction reactions (opposite oxidation) e.g. ethanol to ethanol to ethanoic acid when oxidised to opposite for reduction

Question 29

OH ratio for primary alcohol reactions

Answer 29

ethanol 1:6 Ethanal 1:4 Ethanoic acid 1:2

Question 30

Reduction carboxylic acid

Answer 30

Oxygen removed or hydrogen added

Question 31

Carboxylic acid reacting with base

Answer 31

form salt and water in neutralisation reaction

Question 32

neutralisation reaction carboxylic acid and base when long fatty acid used

Answer 32

the salt formed is soap

Question 33

butter going off

Answer 33

formation of butanoic acid as butter is hydrolysed

Question 34

What helps prevent food from spoiling

Answer 34

Antioxidants which are reducing agents

Question 35

Antioxidants in many brighly coloured fruits

Answer 35

antioxidant compounds called polyphenols - vitamin C

Question 36

Vitamin C reacts to form

Answer 36

dehydroascorbic acid by losing 2 H from the hydroxyl attached to ring part, forming 2 ketones loss H indicates oxidation and 2e- lost - supply of electrons prevent oxidation in other chemicals, causing them instead to be reduced

Question 37

vitamin C reaction formula

Answer 37

C6H8O6 -----> C6H6O6 + 2H +2e-

Question 38

removal of H and loss electrons in vitamin C

Answer 38

indicate this is an oxidation reaction, showing that as an antioxidant, vitamin C itself is oxidised

Question 39

Why do diols have higher bo than alcohols

Answer 39

This is due to the presence of two hydroxyl groups which allow for more hydrogen bonding, contributing to a higher degree of intermolecular attractions.

Question 40

what kind of agent are antioxidants

Answer 40

reducing