CRS – Organic Chemistry – Flashcards
Unlock all answers in this set
Unlock answersquestion
Organic Chemistry
answer
Chemistry of Carbon
question
Chemistry of Carbon
answer
Organic Chemistry
question
State 4 reasons why carbon is so special
answer
- 4 outer electrons - 4 covalent bonds - forms chains or rings - huge number of possible variations
question
State the 4 types of formulae found in Organic Chemistry
answer
- molecular -structural -displayed -skeletal
question
structural formula
answer
CH3CH2CH3
question
What is a functional group?
answer
- groups of atoms that are attached to carbon skeletons -they confer a characteristic set of properties and reactions -they give rise to homologous series
question
- groups of atoms that are attached to carbon skeletons -they confer a characteristic set of properties and reactions -they give rise to homologous series
answer
Functional groups
question
What is a homologous series?
answer
-group of molecules that have the same functional group but differ in the length and structure of the carbon chain
question
Group of molecules that have the same functional group but differ in the length and structure of the carbon chain
answer
Homologous series
question
State the 8 homologous series.
answer
- Alkanes - Alkenes -Arenes -Halogenoalkanes - Aldehydes -Ketones -Carboxylic acids
question
What is the general formula of alkanes?
answer
CnH2n+2
question
Which homologous series has this general formula: CnH2n+2?
answer
Alkanes
question
What 2 types of bonds do alkanes have?
answer
C-C and C-H
question
Why are alkanes not very reactive?
answer
because C-C bonds are not polar and C-H bonds are not significantly polar.
question
Why are alkanes said to be saturated hydrocarbons?
answer
because they only have single bonds (C-C and C-H)
question
How are alkanes classified wrt their bonding.
answer
saturated hydrocarbons
question
What are the bonds present in alkanes consisting of an overlapping between atomic orbitals?
answer
Sigma Bonds
question
State the 10 prefixes used to name the carbon chains.
answer
1. meth- 2. eth- 3.prop- 4. but 5. pent- 6. hex- 7. hept- 8. oct- 9. non- 10. dec-
question
How many carbon does a methane chain have?
answer
1
question
How many carbon does an ethane chain have?
answer
2
question
How many carbon does a propane chain have?
answer
3
question
How many carbon does a butane chain have?
answer
4
question
How many carbon does a pentane chain have?
answer
5
question
How many carbon does a hexane chain have?
answer
6
question
How many carbon does a heptane chain have?
answer
7
question
How many carbon does an octane chain have?
answer
8
question
How many carbon does a nonane chain have?
answer
9
question
How many carbon does a decane chain have?
answer
10
question
What suffix is added to name an unbranched chain?
answer
-ane
question
What suffix is added to name a branched chain?
answer
-yl
question
What prefix is added to name a ring structure?
answer
cyclo-
question
What is the general formula of alkenes?
answer
CnH2n
question
What homologous series has the following general formula: CnH2n?
answer
Alkenes
question
What bonds do alkenes have?
answer
C=C
question
How are alkenes classified according to their bonding?
answer
Unsaturated hydrocarbons
question
Why are alkenes said to be unsaturated hydrocarbons?
answer
Because they have C=C double bonds
question
Why are alkenes more reactive than alkanes?
answer
Because the electrons are not held between the carbons but within an electron cloud above or below the molecule. Positive things are likely to be attracted to the high electron density.
question
Which homologous series has a free rotation around its bonds?
answer
Alkanes
question
Which homologous series has a restricted rotation around its bonds?
answer
Alkenes
question
Which chain is the principle chain in alkanes?
answer
The longest chain
question
Which chain is the principle chain in alkenes?
answer
the chain with the double bond.
question
Which suffix is added to the principle chain when naming alkenes?
answer
-ene
question
Which carbon number do we use to indicate the position of the double bond in alkenes?
answer
the lowest number
question
How are arenes classified according to their structure?
answer
aromatic hydrocarbons
question
What functional group do arenes have?
answer
a benzene ring
question
How are the electron spread in arenes?
answer
They exist in an overlapping p orbital which produces a system of Pi molecular orbitals spread over the entire ring structure.
question
How many Carbons and Hydrogens does a benzene ring have?
answer
6 carbons 6 hydrogens
question
How do you recognise a benzene ring?
answer
6 carbons 6 hydrogens
question
How does benzene achieve the maximum overlap?
answer
it has a planar structure
question
Why does benzene have a planar structure?
answer
To achieve the maximum orbital overlap
question
State the 3 main properties of arenes.
answer
- high degree of energetic stability -undergoes combustion, found in crude oil and petrol - relatively unreactive
question
Why are arenes relatively stable?
answer
Because of their delocalised Pi molecular orbitals.
question
What property of arenes is due to their delocalised Pi molecular orbitals?
answer
high degree of energetic stability
question
Where are arenes found?
answer
- in crude oil - in petrol
question
What word do we add to name arenes?
answer
-benzene
question
What are the 2 other names for halogenoalkanes?
answer
- haloalkanes - alkyl halides
question
What are the 2 other names for haloalkanes?
answer
-halogenoalkanes - alkyl halides
question
What are the 2 other names for alkyl halides?
answer
- halogenoalkanes - haloalkanes
question
Which atoms are found in halogenoalkanes?
answer
halogen atoms
question
State the 4 halogen atoms
answer
- fluorine - chlorine -bromine - iodine
question
What does aliphatic mean?
answer
straight chain
question
How is a straight chain compound called?
answer
Aliphatic
question
How is a ring compound called?
answer
Aromatic
question
What is the opposite of aliphatic?
answer
aromatic
question
What is the opposite of aromatic?
answer
Aliphatic
question
What is the general formula of alcohols?
answer
CnH2n+1OH
question
What suffix do we add when naming alcohols?
answer
-ol
question
What common functional group do aldehydes and ketones have?
answer
carbonyl group (C=O)
question
Which homologous series have a carbonyl group?
answer
- Aldehydes - Ketones
question
What functional group do alhedydes have?
answer
Carbonyl (C=O)
question
What functional group do ketones have?
answer
Carbonyl (C=O)
question
Where is the carbonyl group found in aldehydes?
answer
at the end of the carbon chain
question
Where is the carbonyl group found in ketones?
answer
in the middle of the chain
question
What suffix do we add when naming aldehydes?
answer
-al
question
What suffix do we add when naming ketones?
answer
-one
question
What is the functional group found in carboxylic acid?
answer
Carboxyl (-COOH)
question
How do we name branched carboxylic acids?
answer
count from the carbon atom in the -COOH group
question
What homologous series has a hydroxyl group?
answer
alcohols
question
What homologous series has a carboxyl group?
answer
Carboxylic acids
question
What is the common name of methanoic acid?
answer
Formic acid
question
What is the common name of ethanoic acid?
answer
Acetic acid
question
What is the common name of propanoic acid?
answer
Propionic acid
question
What is the common name of butanoic acid?
answer
Butyric acid
question
What is the common name of pentanoic acid?
answer
Valeric acid
question
What is the common name of hexanoic acid?
answer
Caproic acid
question
What is the actual name of Formic acid?
answer
Methanoic acid
question
What is the actual name of Acetic acid?
answer
Ethanoic acid
question
What is the actual name of Propionic acid?
answer
Propanoic acid
question
What is the actual name of Butyric acid?
answer
Butanoic acid
question
What is the actual name of Valeric acid?
answer
Pentanoic acid
question
What is the actual name of Caproic acid?
answer
Hexanoic acid
question
What is the natural origin of methanoic acid?
answer
ants
question
What is the natural origin of ethanoic acid?
answer
vinegar
question
What is the natural origin of propanoic acid?
answer
acne bacteria
question
What is the natural origin of butanoic acid?
answer
sheep, buffalo milk
question
What is the natural origin of pentanoic acid?
answer
valeria plant
question
What is the natural origin of hexanoic acid?
answer
goat
question
What is the natural origin of Formic acid?
answer
ants
question
What is the natural origin of Acetic acid?
answer
vinegar
question
What is the natural origin of Propionic acid?
answer
acne bacteria
question
What is the natural origin of Butyric acid?
answer
sheep, buffalo milk
question
What is the natural origin of Valeric acid?
answer
valeria plant
question
What is the natural origin of Caproic acid?
answer
goat
question
Which acid is found in ants?
answer
Formic acid (=methanoic acid)
question
Which acid is found in vinegar?
answer
Acetic acid (=ethanoic acid)
question
Which acid is found in acne bacteria?
answer
Propionic acid (=propanoic acid)
question
Which acid is found in sheep and buffalo milk?
answer
Butyric acid (=butanoic acid)
question
Which acid is found in valeria plant?
answer
Valeric acid (=pentanoic acid)
question
Which acid is found in goats?
answer
Caproic acid (=hexanoic acid)
question
What is a Fatty acid?
answer
a long-chain unbranched carboxylic acid
question
What is the common name of dodecanoic acid?
answer
lauric acid
question
What is the common name of tetradecanoic acid?
answer
myristic acid
question
What is the common name of hexadecanoic acid?
answer
palmitic acid
question
What is the common name of hexadecan-9-enoic acid?
answer
palmitoleic acid
question
What is the common name of octadecanoic acid?
answer
stearic acid
question
What is the common name of octadecan-cis-9-enoic acid?
answer
Oleic acid
question
Where is malic acid found?
answer
in various fruits
question
Where is pyruvic acid found?
answer
it's a metabolic intermediate
question
Where is niacin found?
answer
it's a vitamin
question
Where is citric acid found?
answer
in citrus fruits
question
Where is biotin found?
answer
its a cell growth factor
question
Where is abietic acid found?
answer
in pine resin
question
Where is cholic acid found?
answer
in bile
question
What governs the physical properties of carboxylic acids?
answer
their ability to form hydrogen bonds
question
How does the boiling points of carboxylic acids vary in comparison to those of alcohols of similar sizes?
answer
The boiling point of carboxylic acids is higher than that of alcohols of similar sizes.
question
Explain why the boiling point of carboxylic acids is higher than that of alcohols of similar sizes.
answer
-The higher boiling point of carboxylic acids is due to hydrogen bonds. -In a pure carboxylic acid, hydrogen bonding can occur between 2 molecules to form a dimer. -This dimer immediately doubles the size of the molecule -As the molecule is bigger, the number if instantaneous dipole - induced dipole and intermolecular forces is increased (between one of these dimers and its neighbours). -So it is more difficult to separate the molecules -So carboxylic acids have a higher boiling point than equivalent alcohols
question
Describe the solubility in water of carboxylic acids.
answer
- in water, carboxylic acids don't dimerise - carboxylic acids containing up to 4 carbon atoms will mix up with water in any proportion -solubility of larger acids decreases with size
question
Explain why carboxylic acids don't dimerise in water but they do in non polar solvents.
answer
- in water, carboxylic acids form a lot of hydrogen bonds with water molecules - in polar solvents, there is no other bond possible so dimers are formed, inducing permanent dipoles
question
Explain why carboxylic acids are acids.
answer
-An acid is a compound that donates H+ in solution - carboxylic acids can give out the H present on the hydroxyl group (OH)
question
Explain why carboxylic acids are more acidic than alcohols.
answer
1. C=O - the C=O bond has an effect on the O-H bond - it draws the e- away (towards it), making the O-H bond weaker (more likely to dissociate and release an H+) 2. Anion Stability - the interactions of Pi orbitals alows the delocalisation of e- around the carboxylic acid -so the charge is no longer localised to 1 atom -this stabilises the anion (resonance structure)
question
Give the 2 main reasons why carboxylic acids are more acidic than alcohols
answer
1. C=O e- drawing effect 2. Anion stability
question
What is the resonance structure in carboxylic acids?
answer
-its is the interaction of Pi orbitals which allows the delocalisation of e- around the carboxylic acid in the anion (spread of the negaive charge between the 2O) -it stabilises the anion -that is one of the reasons why carboxylic acids are more acid than alcohols of similar sizes
question
Give the equation of the dissociation of ethanoic acid.
answer
- CH3COOH + H2O CH3COO- + H3O+ or -CH3COOH(aq) CH3COO- + H+
question
What type of acids are carboxylic acids?
answer
weak acids
question
Explain why carboxylic acids are said to be 'weak acids'?
answer
Their dissociation is reversible and only partial
question
In the dissociation of ethanoic acid, what portion of ethanoic acid reacts to form ions at any one time?
answer
1%
question
Describe the dissociation of carboxylic acids in one sentence.
answer
In solution, a H+ ion is transferred from the carboxylic acid to a water molecule.
question
Recall how the pKa relates to the pH.
answer
- The lower the pKa, the lower the pH, the stronger the acid (the more dissociation occurs)
question
Which substituents make a weaker carboxylic acid?
answer
alkyl groups
question
Which substituents make a stronger carboxylic acid?
answer
halogens
question
What effect has the addition of alkyl groups on a carboxylic acid?
answer
- the alkyl groups push the e- towards the carboxyl group -this makes the anion more negative, so less stable (more likely to reform the acid) -and it makes the O-H bond more stable (prevents it from becoming an ion by preventing the shift of the H e- to go towards the O) -so adding an alkyl goup makes it a weaker acid.
question
What effect has the addition of halogens on a carboxylic acid?
answer
- halogens draw e- away (towards them) - this makes the anion less negative, so more stable (by spreading the negative charge) -and it makes the O-H bond weaker (e- are shifted towards thr H which is more likely to break) -so adding a halogen makes it a stronger acid. -the closer the halogens are from the carboxyl group, the stronger the effect
question
How does the drawing effect of halogens vary with their proximity to the carboxyl group in carboxylic acids?
answer
The closer the halogens are to the carboxyl group, the stronger their effect.
question
Describe how you would distinguish between a carboxylic acid, an aldehyde, an ketone and an inorganic acid (4 ways).
answer
- pH: Highest pH for carbonyls (aldehydes & ketones) - less acidic - Benedict's: no further oxidation of ketones - Brady's: no reaction with carboxylic acids - Neutralisation
question
What are the 2 functional groups involved in an ester bond?
answer
- carboxylic acid -COOH - alcohol -OH
question
What type of reaction forms ethyl ethanoate?
answer
esterification
question
Which two substances react together in an esterification reaction to form ethyl ethanoate?
answer
- ethanol - ethanoic acid
question
Which catalyst is usually used to form ethyl ethanoate?
answer
concentrated sulphuric acid
question
What is the role of concentrated sulphuric acid in the formation of ethyl ethanoate?
answer
catalyst
question
State the two main things involved in esterification?
answer
- association of -COOH with -OH - release of a water molecule
question
In esterification, which compound provides 1 H atom for the formation of a water molecule?
answer
the carboxylic acid
question
In esterification, which compound provides 1 H and 1 O atom for the formation of a water molecule?
answer
tthe alcohol
