Unit 2 - Nature's Chemistry Flashcards
1
Q
What is the general formula for alkanes?
A
Cn H2n+2
2
Q
What are the first eight alkanes?
What is the pneumonic to remember these?
A
Methane, Ethane, Propane, Butane, Pentane, Hexane, Heptane, Octane
Monsters Eat People But People Have Hairy Oster’s
3
Q
Are hydrocarbons soluble in water?
What does this say about their overall polarity?
A
Insoluble
Non-Polar
4
Q
Are alkanes saturated or unsaturated?
A
Saturated - all carbon to carbon single bonds
5
Q
What is the general formula for alkenes?
A
Cn H2n
6
Q
What are the first alkenes?
A
Ethene, Propene, But-1-ene
7
Q
What does the -1- mean in alkenes?
A
The position of the double bond
8
Q
Are alkenes saturated or unsaturated?
A
Unsaturated - contain a carbon to carbon double bond
9
Q
Why isn’t there a methene?
A
Alkenes require a C=C, and methane only has one carbon so cannot form this bond, and therefore no alkene is formed
10
Q
Why are alkenes more reactive than alkanes?
A
Have a C=C double bond that can be broken in a reaction
11
Q
What is the test for an alkene?
A
Will turn orange bromine colourless immediately
12
Q
What is a hydrocarbon?
A
A compound make up of only carbon and hydrogen
13
Q
What is a homologous series?
A
A family of hydrocarbons with similar chemical properties that share a general formula
14
Q
What is the general formula for cycloalkanes?
A
CnH2n
15
Q
What is the first cycloalkane?
A
Cyclopropane
16
Q
What is the general formula for cycloalkenes?
A
CnH2n-2
17
Q
What are the steps for naming and alkane?
A
Find the longest chain of hydrogens
Identify the branch and name it
(1 carbon = methyl, 2 carbon = ethyl)
Number the carbons on the chain so the branch is at the lowest number
Write name as : # branch is on chain - branch type chain type
e.g. 2 - methylpentane
18
Q
What are the steps for naming an alkene?
A
Find the longest possible chain of hydrocarbons
Number the chain so the double bond is at the lowest possible number
Identify branch and name it
Write out as : #branch - branch type chain - # = - type
e.g. 2-methylpent-1-ane
19
Q
What is an isomer?
A
Compounds with the same molecular formula but a different structural formula
20
Q
What are the isomers of alkanes?
A
Branched alkanes
21
Q
What are the isomers of alkenes?
A
Cycloalkanes
22
Q
What type of hydrocarbon undergoes addition reactions?
A
Alkenes
23
Q
What is hydrogenation?
A
The reaction between an alkene and hydrogen
24
Q
What is hydration?
A
The reaction between an alkene and water
Forms and OH branch
25
In a addition reaction, where do the new molecules add?
Where the old double bond was
26
What is an alcohol?
A large group of of organic molecules which contain at least one hydroxide (OH) group as the functional group.
27
What is the general formula for alcohols?
CnH2n+1 OH
28
How do you name an alcohol?
Select longest hydrocarbon chain and name it
Number hydrocarbons from end nearest the hydroxide group - hydroxide > branch
Name branches with their positions
*Be prepared to work backwards*
29
Why do alcohols mix well with water?
Have hydrogen bonds
30
What is meant by a dihydric alcohol?
An alcohol that contains two hydroxyl groups
31
What is the removal of water referred to as?
Dehydration
32
What are the three classifications of alcohols?
Primary
Secondary
Tertiary
33
What is a primary alcohol?
An alcohol with 2 (or 3) hydrogens attached to the carbon with the hydroxyl group
Attached to 1 carbon
34
What is a secondary alcohol?
An alcohol with one hydrogen atom attached to the carbon with the hydroxyl group
Attached to two carbons
35
What is a tertiary alcohol?
An alcohol that has no hydrogen atoms attached to the carbon with the hydroxyl group
Attached to three carbons (branched)
36
What are the products from combusting an alcohol?
Water and Carbon Dioxide
37
What is combustion?
An extreme form of oxidation
38
What is the chemical formula for ethanol?
C2H5OH
39
What happens in mild oxidation?
Functional group is altered
40
What type of products are formed when an alcohol undergoes mild oxidation?
New organic molecules
41
What are the mild oxidising agents used to oxidise alcohols?
```
Acidified potassium dichromate
Acidified potassium permanganate
Benedict's solution
Hot copper(11) oxide
Tollen's reagent
```
42
What alcohols don't go through mild oxidation?
Tertiary alcohols
43
What is the functional group in aldehydes and ketones?
Carbonyl group
44
After undergoing mild oxidation, what do primary alcohols become?
Aldehydes (alkanals)
45
Where is the carbonyl group in aldehydes?
At the end (the last/first carbon in the chain)
46
After undergoing mild oxidation, what does secondary alcohols become?
Ketones (alkanones)
47
Where is the carbonyl group in ketones?
In the middle of the chain
48
What is the general formula for the alkanals?
CnH2nO
49
What is the general formula for the ketones?
CnH2nO
50
What is the relation between the ketones and alkanals?
Isomers
51
What are everyday uses of ketones?
Acetone/propanone -> nail polish remover & paint thinner
Acne treatments
Butanone -> production of textiles, varnishes, paint remover, plastics
Cyclohexanone -> production of nylon
Glue
Cleaning agents
Hormones (progesterone, testosterone, cortisone (adrenal) etc)
Tanning
Decreases appetite, used in weight loss programs
Methadone -> cures addiction of opiates (heroin, opium, morphine)
52
What are everyday uses of aldehydes?
Methanal -> embalming
Phenylmethanal (benzaldehyde) -> perfumes, flavourings, cosmetic products, dyes
Ethanal -> sleep inducing drugs, causes hangovers
Pharmaceuticals
Resin
53
What colour change would you see when an aldehyde mixed with acidified potassium dichromate?
Orange to blue/green
54
What would you see when an aldehyde mixed with benedict's solution?
Blue to brick red
55
What would you see when an aldehyde mixed with tollen's reagent?
Silver mirror formed
56
Why can aldehyde's be further oxidised but ketones cannot?
Because of the position of the carbonyl group
57
What to aldehyde's form when oxidised further?
Alkanoic acids
58
Where is the carboxyl group in alkanoic acids?
At the end of the chain
59
What is the first member of the alkanoic acids?
Methanoic acid
60
Describe an experiment to test for alkanals?
Place it hot water bath with a solution of either acidified potassium dichromate, benedict's solution or tollen's reagent.
If a colour change is observed, a reaction has taken place (oxidation) and the solution is an aldehyde
61
Pentan-3-ol is an example of a _____ alcohol?
Secondary
62
When an alcohol is oxidised what happens to the ratio of oxygen atoms to hydrogen atoms?
Increases
63
What is the functional group in a ketone?
Carbonyl group
64
What is the colour change when acidified potassium dichromate solution reacts with an aldehyde?
Orange to blue green
65
In what way is the structure of an aldehyde different to the structure of a ketone?
Carbonyl group on aldehyde is on the first carbon, carbonyl group on ketone is between the start and the end of the carbon chain.
66
What is the colour change when ethanal reacts with acidified potassium dichromate?
Ethanal = aldehyde = primary
Further Oxidation
Colour change = Orange to brown/darker
67
What are the names for the reaction in which esters are made?
Condensation
| Esterification
68
What scent to esters give off?
A sweet smell]
69
What happens during a condensation reaction?
The functional group from a carboxylic acid and am alcohol functional group
70
How do you name esters?
First name = name of alcohol prefix + yl
| Second Name = carboxylic acid prefix +oate
71
What ester would be formed by the reaction of ethanoic acid and propan-1-ol?
proply ethanoate
72
How would you identify an ester?
Ends in oate
| Has an ester link/ester functional group
73
What is the functional group of an ester?
C double bond O, O
| Carbon double bonded to an oxygen and single bonded to another oxygen
74
How should you draw structure for a condensation reaction?
Full structural formula
| Make functional groups face each other
75
Why do esters form a layer on top of water?
Can't mix with water as water is polar and esters are non polar
76
How would the rate of ester formation be increased?
Increased temperature
Use of concentrated sulfuric acid to lower the activation energy
Use of concentrated sulfuric acid to remove water from the products and shift the equilibrium
77
What are the uses of esters?
```
Pleasant fruity smells
Food
Flavourings
Perfumes
Solvents (industrial)
```
78
What is the catalyst in esterification?
Concentrated sulfuric acid
79
What is the reverse esterification reaction called?
Hydrolysis
80
What is the catalyst in a hydrolysis reaction?
An alkali
| e.g. sodium hydroxide
81
Give examples of natural esters.
Fats
| Oils
82
Where are natural fats usually sourced from?
Animals
83
Where are natural oils usually sourced from?
Vegetables and Marine
84
How are natural esters formed?
Reaction between long chain carboxylic acid and trihydric alcohols
85
What are long chain carboxylic acids referred to as?
Fatty acids
86
Are fatty acids saturated or unsaturated?
Either/both
87
What alcohol takes part in the production of natural esters?
Propan-1,2,3 - triol
| trihydric alcohol
88
How would you tell if a product would be saturated or unsaturated when given a formula?
If number of hydrogens > 2 x the number of carbons = saturated
If number of hydrogens < 2 x the number of carbons = unsaturated
89
Are fats saturated or unsaturated?
Saturated?
90
Are oils saturated or unsaturated?
Unsaturated
91
What is the ratio for glycerol to fatty acid chains?
1 glycerol molecule : 3 fatty chains
92
Why do fats have higher melting points than oils?
Molecules are packed closely together so have stronger Van Der Waals forces between molecules increasing the melting and boiling point
93
Why so oils have a lower melting point than fats?
Molecules are unable to pack closely together due to their irregular structure resulting in weaker van der waals forces and so lower melting and boiling points
94
What is hydrogenation?
A reaction which converts unsaturated compounds into more saturated ones
'hardening reaction'
95
What is hydrogenation used to do?
Change oils into margarine
96
What catalyst is used in hydrogenation reactions?
Nickel
97
What happens in a hydrogenation reaction?
Hydrogen is added to compounds to remove/reduce the number of carbon to carbon double bonds
98
How can the degree of saturation in a fat or oil be determined?
By the iodine number
99
What does a greater iodine number suggest?
More c=c double bonds
100
How are soaps made?
Hydrolysis of fats and oils with an alkali
101
What are the products of an alkali hydrolysis of fats and oils?
Water soluble ionic salt of the carboxylic acid
| Glycerol
102
What are the two parts of soap?
Head and tail
103
What are the properties of the head and tail of soap?
Head -> hydrophilic, polar, water soluble, ionic
| Tail -> hydrophobic, non polar, oil soluble, covalent
104
Describe the cleaning action of soap
Non polar hydrophobic tail attracts non-polar fat/oil molecules
Polar hydrophilic heads are attracted to polar water molecules
Large fatty molecules are broken into small lumps called micelles resulting in a suspension of fatty material in the water
105
What is an emulsifier?
Molecule that allows non polar and polar molecules to mix (i.e. soap)
106
What is emulsion?
Mixture of non polar and polar substances
107
Why do we need proteins?
For growth and repair
108
What are proteins components of?
Animal tissue :muscle, hair, nails, skin
109
What are proteins made from?
Amino acids - hydrogen and nitrogen
110
What is the test to confirm the presence of nitrogen?
Soda lime with protein heated up in a boiling tube with a mineral wool bung and a piece of wet pH paper at the mouth.
pH paper should turn blue
111
What are proteins in chemistry?
Natural polymers made up of amino acid monomers
112
What functional group do amino acids have?
Carboxyl and amine
113
What is the amine functional group?
NH2
114
What is an essential amino acid?
An amino acid that we get from our diet
115
What can happen if an essential amino acid is missing from our diet?
Deficiencies
116
What reaction turns monomer amino acids into a polymer protein?
Condensation polymerisation
117
How would you identify a protein?
From the functional group
118
What is the functional group in proteins?
Amide / Peptide Link
119
Give the reactants and products of a condensation polymerisation reaction.
Reactants -> amino acids
| Products -> proteins and water
120
In a condensation polymerisation reaction, what does the water form from?
OH off of carboxyl group
| H off of Amine group
121
What is the polarity of amide links?
Polar
122
What intermolecular forces are present in proteins and where?
Hydrogen bonds between H and O
123
What is the reverse reaction to a condensation polymerisation reaction?
Hydrolysis
124
Where does the water add to in a hydrolysis of a protein?
OH onto C=0
| H onto nitrogen
125
What are the two classifications of proteins?
Fibrous
| Globular
126
What are the characteristics of fibrous proteins?
Long and thin - penne pasta
| Major structural materials of animal tissue
127
Give examples of fibrous proteins.
Skin
Muscle
Hair
Nails
128
What is the main purpose of globular proteins?
Maintenance and regulation life processes
| Spaghetti structure
129
Give examples of globular proteins.
Enzymes
Hormones
e.g. insulin and haemoglobin
130
What are enzymes?
Natural catalysts that decrease the activation energy of biological reactions so they can take place at body temperature
131
Give a method of making a soap
Weight out mass of oil in a beaker
Add dripping
Add a shaving of soap
Slowly heat to 95 degrees with a Bunsen
Weigh sample of sodium hydroxide pellets and dissolve in water
Add sodium hydroxide solution to hot fat mixture slowly
Mixture should stiffen
Cool solution and add water at 65 degrees
Stir and heat for another 30 minutes to form a thick paste
Heat hot brine and add to solution
Stir until soap breaks away
Leave overnight
132
How do we taste food?
Through sense of smell and taste
133
What is volatility?
A measure of ease of evaporation
134
Why are small non polar easier to evaporate than larger non polar molecules?
Have very low mp and bp
135
When do volatile flavour molecules evaporate?
When they have a low boiling point
136
What determines if a flavour molecule is water or fat soluble?
The structure of the molecule
| Type of intermolecular bonding
137
What intermolecular force do very volatile molecules have?
London Dispersion Forces
138
What are antioxidants?
Reducing agents
139
What do antioxidants do?
Provide electrons to prevent the oxidation of fats/oils of foods
Prolong shelf life
140
Give two pieces of evidence for the oxidation of ascorbic acid.
Loss of electrons
| Decreased O:H ratio
141
How many carbons are present in one isoprene unit?
5
142
What do fragrances contain?
Essential oils
143
What is meant by an essential oil?
An oil that gives off an essence (flavour, smell/aroma)
144
Why do essential oils evaporate easily?
Volatile (low bp)
145
Are essential oils polar or non-polar?
Non polar
146
What are terpenes?
Key component of essential oils
147
What is the systematic name for isoprene?
2-methylbutan-1,3-diene
148
What is the general formula for isoprene?
(C5H8)n
149
What are terpenes made up of?
Linked isoprene units
150
How can isoprene's link together?
Head to tail - linear
| Ring structure
151
What is an oxidised terpene known as?
Terpanoid
152
What types of UV pose a threat to humans?
UVA and UVB
153
How does sunblock work?
Chemicals absorb UV radiation
| Reflect UV radiation away from the skin
154
What is a free radical?
Atoms/molecules which have unpaired electrons that makes them extremely reactive with potential to harm cells
155
What are the stages of a free radical chain reaction?
Initiation
Propagation
Termination
156
How do you identify the initiation stage of free radicals?
Free radicals are on the right hand side
157
How do you identify the propagation stage of free radicals?
Free radicals are on both sides of the equation
158
How do you identify the termination stage of free radicals?
Free radicals are on left hand side of the equation
159
What are free radical scavengers also known as?
Antioxidants
160
What are free radical scavengers?
Molecules react with free radicals to produce stable molecules and thus terminates the reaction
