S5 - Unit 1 & 2 Flashcards
How can alcohols be classified?
Depending on how many carbons are attached to a hydroxyl group
What name is given to an alcohol with 1 carbon attached to the hydroxyl group?
Primary
What name is given to an alcohol with 2 carbons attached to the hydroxyl group?
Secondary
What name is given to an alcohol with 3 carbons attached to the hydroxyl group?
Tertiary
What name is given to alcohols with more than one hydroxyl group?
Polyhydric alcohol
How can alcohols be oxidised?
By adding oxygen or removing hydrogen
How many steps can primary alcohols undergo in oxidation?
What happens in each step?
What is the product of each step?
- 2
- Removal of hydrogen and addition of
oxygen between carbon and hydrogen - Alcohol ~> aldehyde
Aldehyde ~> acid
How many steps can secondary alcohols undergo in oxidation?
What happens in each step?
What is the product of each step?
- 1
- Removal of hydrogen
- Alcohol ~> ketone
How many steps can tertiary alcohols undergo in oxidation?
What happens in each step?
What is the product of each step?
- 0
- N/A
- N/A
How to aldehydes and ketones differ?
Aldehydes have the function group (carbonyl) always attached to the first carbon whereas in ketones the functional group (carbonyl) is attached to two other carbons
What is the general formula for alkanals?
CnH2nO
What is the general formula for alkanones?
CnH2nO
What are the oxidising agents learned about?
- Acidified potassium dichromate solution
- Fehling’s solution
- Tollen’s reagent
What are the observations made with each of the oxidising agents?
A.P.D.S = orange ~> green
F.S = Blue ~> orange
T.R = Colourless ~> silver
What is the corresponding salt name for each carboxylic acid?
Methanoate
Ethanoate
Propanoate
Butanoate
Pentanoate
What is the formula for a salt produced by a carboxylic acid and a metal?
CnH2n+1COO-__+
(__ = metal)
How are esters produced?
By carboxylic acids undergoing condensation reactions with alcohols
What is a condensation reaction?
When two molecules join together, usually in the presence of a catalyst, with the elimination of water or another simple molecule
How do you name esters?
Alcohols name + carboxylic acid salt name
What is the catalyst in a condensation and hydrolysis reaction?
Concentrated sulphuric acid
What is the role of a wet paper towel when making esters?
Acts as a condenser
Why is something used to cover the top of the test tube when making esters?
To contain any chemicals that may spurt out
What is used to neutralise any remaining acid in the ester once it has been formed?
Sodium hydrocarbonate
What properties do esters have?
- Usually have sweet smells
- More volatile than carboxylic acids
- Insoluble in water
- Much less polar than carboxylic acids
What are come uses of esters?
-Used as flavourings
- Used in perfumes
- Used as solvents
What is the functional group for aldehydes?
Carbonyl
What is the functional group for ketones?
Carbonyl
What does the carbonyl functional group structure look like?
.
|
—-C=O
|
What is hydrolysis?
The opposite of condensation - when water is added to break up the molecule
What is the homologous series for the alkanones?
Ketones
What is the homologous series for the alkanals?
Aldehydes
What is the equation for carboxylic acids reacting with a metal?
Acid + metal ~> salt + hydrogen
What else is produced when an ester formed?
Water
What are diatomic elements?
Two atoms joined together by a shared pair of electrons
What are discrete molecules?
Small groups of atoms held together by strong covalent bonds inside the molecule and weak intermolecular forces between the molecule
What elements are most commonly discrete?
The diatomic elements
What are the only elements that can form covalent networks?
Carbon (in the form of diamond or graphite), boron and silicon
What are monatomic elements and what are examples?
Single, unattached atoms.
Elements in group 8 (they have a full outer shell of electrons
What happens when monatomic elements are cooled?
The atoms move closer and are held by week LDF’s
What are London Dispersion Forces?
Weak, short lived bonds between atoms and molecules
How do LDF’s occur?
Due to the positioning of the electrons in the outer shell
What happens if the electrons are unevenly distributed in the shells?
It can cause a temporary dipole allowing the atoms to be attracted to each other
What happens to the m.p and the b.p as you go down group 1 and why?
They decrease as the atoms become less tightly held together.
What can cause metallic bonds to get weaker?
If the delocalised electrons move further away from the nuclei of the positive ions
What happens to the m.p and b.p as you go down group 7 and why?
They increase as the LDF’s between the molecules increases with atomic number.
What does an increased number in electrons mean?
An increase in the number of shells and therefore greater LDF’s
What are polar covalent bonds?
When atoms with different electronegativities form covalent bonds
What are non-polar covalent bonds?
When atoms of the same electronegativities form covalent bonds
Which element (the one with less electronegativity or the one with greater) will have a slightly negative charge?
The element with a greater electronegativity
Which element (the one with less electronegativity or the one with greater) will have a slightly positive charge?
The element with a smaller electronegativity
Ionic bonds have … electronegativites.
- Very high
- High
- Low
- No
High
Covalent bonds have … electronegativites.
- Very high
- High
- Low
- No
No
Polar covalent bonds have … electronegativites.
- Very high
- High
- Low
- No
Low
What are intramolecular forces?
Forces that hold the atoms within a molecule together
What are intermolecular forces?
Forces that exist between molecules
What are the three van der Waal’s forces?
- LDF’s
- Permanent dipole - permanent dipole (pd. pd.)
- Hydrogen
What do pd. pd forces occur between?
Atoms in compounds with different electronegativities
When does hydrogen bonding occur in compounds?
When N/O/F is linked to hydrogen
Why do some compounds containing hydrogen have higher boiling points than expected?
Because hydrogen bonding holds the molecules together more tightly than other van der Waal forces
What is viscosity directly proportional to?
The gfm of a molecule
What else, other than a high gfm, might cause a substance to be viscous?
Hydroxyl groups
What happens to the viscosity of a substance as the number of hydroxyl groups are increased?
It increases
What will dissolve polar and ionic substances?
Polar covalent molecules
What will dissolve non-polar substances?
A non-polar solvent
What does miscible mean?
Soluble
What does immiscible mean?
Insoluble
What does hydrogen bonding do the the miscibility of a substance?
Increases it
What are the 3 naturally occurring fats and oils?
- Animal fat
- Plant oil
- Marine Oil
What are examples of animal fats?
Lard and suet
What are examples of plant oils?
Sunflower and coconut
What are examples of marine oils?
Cod liver
What food group provides more energy per gram; fats or carbohydrates?
Fats
What properties do fats have?
Insoluble and group together
What molecule are fats and oils both based on?
Glycerol
What is the structure of glycerol?
What can each hydroxyl group in glycerol combine with?
- A carboxylic acid molecule
What name is given to the carboxylic acids that react with glycerol?
Fatty acids
How can you tell if a fatty acid is unsaturated or saturated?
If it is saturated the no. of H’s is more than double the no. of C’s
If it is unsaturated the no. of H’s is less than double the no. of C’s
What is produced when glycerol and carboxylic acids react?
Fats or oils
What reaction is undergone to produce a fat or oil?
Condensation
Complete the sentence
Fats and oils are … of glycerol and fatty acids.
Esters
What do C=C introduce fats and oils to?
‘Kinks’
Why are fats solid at room temperature?
They are compact and can pack closely together, resulting in a lot of LDF’s
Why are oils usually liquid at room temperature?
They have a more irregular shape, meaning they cannot pack as closely together resulting in less LDF’s
What is the structure of fats and oils and what makes them different?
- Oils have ‘kinks’ (irregular shape)
What is hydrogenation?
The catalytic addition of hydrogen to an unsaturated oil which hardens it and increases it’s boiling and melting points
What determines the ‘iodine number’?
The number of C=C in a fat or oil
(the greater the number of C=C, the greater the iodine number)
What are soaps?
Salts of fatty acids
How are soaps made?
The neutralisation of a fatty acid
What is the structure of a soap?
Complete the sentences:
The ‘tail’ of a soap is…
The ‘head’ of a soap is…
- Hydrophobic
- Hydrophilic
What properties do soaps have?
Hydrophobic, oil soluble and non-polar
How is grease removed with soap?
- The soaps hydrophobic covalent tail interacts with the grease
- Agitation and the strong attraction between the ionic head and the water dislodge the grease
- The grease droplets repel each other due to their negative heads and therefore don’t join back together
What makes water ‘hard’?
It contains Ca2+ and Mg2+ ions
What makes hard water different to water?
It doesn’t form a lather with normal soaps and forms scum instead
How do you make an emulsifying agent?
By reacting glycerol with one fatty acid
What are all the different types of proteins?
- Muscle fibres
- Cell structure
- Hormones
- Binding proteins
- Structures ie: hair, nails
- All enzymes
How can proteins be classified?
According to their shape.
Either globular or fibrous
What does a fibrous protein consist of?
- Chains of interwoven polypeptides
- Polypeptide chains that are held together by hydrogen bonding
What is an example of fibrous proteins?
Hair
What are globular proteins?
Polypeptide chains coiled together in spherical shapes
What is an example of globular proteins?
Enzymes
What does an amino acid look like?
What type of link form between the two groups producing an amino acid?
An amide link
What does an amide link look like?
What is produced when 2 amino acids join together?
A polypeptide (protein) and Water
What type of reaction produces a polypeptide?
Condensation
What reaction break down proteins?
Hydrolysis
What type of reaction takes place in digestion?
Hydrolysis
What are essential amino acids?
Amino acids our body needs but cannot produce
What factors can denature an enzyme?
pH and temp.
What happens when an enzyme is denatured?
It stops working
What is the optimum temp. for enzymes in the human body?
40 degrees C
What features do soapless detergents have?
The head is hydrophilic/polar/ionic/can water soluble.
The tail is hydrophobic/non-polar/non-polar/ fat soluble.
How do emulsifiers prevent the separation of liquids?
Emulsifiers have two parts: a hydrophobic part and a hydrophilic part.
The hydrophobic part dissolves in non-polar liquids whilst the hydrophilic part dissolves in polar liquids.
What process makes soap?
Alkaline hydrolysis of fats/oils with sodium/potassium hydroxide
What is the process of making a soap called?
Saponification
What are essential oils?
Concentrated extracts of volatile, non-water soluble aroma compounds
What are essential oils used in?
Perfumes
Flavouring foods
Cleaning products
Cosmetic products
Preventing the oxidation of food
What makes up essential oils?
Terpenes
What makes up terpenes?
Isoprene units
What does an isoprene unit look like?
What is the product of the oxidation of terpenes?
Terpenoids
How many carbons are in an isoprene unit?
5
What are free radical scavenger?
Molecules which react with free radicals to form stable molecules and prevent chain reactions
What are examples of free radical scavengers?
Melatonin and vitamin E
What is the cause of sunburn?
UV light breaking bonds within molecules
What is formed when UV light breaks bonds?
Free radicals
What are the three steps of free radical chain reactions?
- Initiation
- Propagation
- Termination
What does the first stage of a free radical chain reaction involve?
What does the second stage of a free radical chain reaction involve?
What does the third stage of a free radical chain reaction involve?
How does sunscreen protect against UV light?
It reflects it away from our skin
What is meant by the term ‘free radical’?
An atom with an unpaired electron
Why must titration reactions be carried out under acidic conditions?
To provide H ions
