29: Naming and Physical Properties of Carbon Compounds Flashcards
What is the name of the functional group of alkanes?
There is no functional group since all bonds in alkane molecules are carbon-hydrogen single bonds or carbon-carbon single bonds.
What is the general formula of alkanes?
CnH2n+2
What is the name of the functional group of alkenes?
Carbon-carbon double bond
What is the general formula of alkenes?
CnH2n
What is the suffix of alkenes?
-ene
What is the name of the functional group of haloalkanes?
Carbon-halogen single bond (-X, where X is a halogen)
What is the general formula of haloalkanes?
RX, where X is a halogen.
What is the prefix of haloalkanes?
fluoro- / chloro- / bromo- / iodo-
What is the name of the functional group of alcohols?
Hydroxyl group
What is the general formula of alcohols?
ROH
What is the suffix of alcohols?
-ol
What is the name of the functional group of aldehydes?
Carbonyl group
What is the general formula of aldehydes?
(H or R)CHO
What is the suffix of aldehydes?
-al
What is the name of the functional group of ketones?
Carbonyl group
What is the general formula of ketones?
R1COR2
What is the suffix of ketones?
-one
What is the name of the functional group of carboxylic acids?
Carboxyl group
What is the general formula of carboxylic acids?
(H or R)COOH
What is the suffix of carboxylic acids?
-oic acid / -dioic acid
What is the name of the functional group of esters?
Ester group
What is the general formula of esters?
(H or R1)COOR2
What is the suffix of esters?
-yl -oate
What is the name of the functional group of unsubstituted amides?
Amide functional group
What is the formula of the functional group of unsubstituted amides?
CONH2
What is the general formula of unsubstituted amides?
(H or R)CONH2
What is the suffix of unsubstituted amides?
-amide
What is the name of the functional group of primary amines?
Amine functional group
What is the formula of the functional group of primary amines?
NH2
What is the general formula of primary amines?
RNH2
What is the suffix of primary amines?
-amine
What are the trends of boiling points within a homologous series?
As the carbon chain length increases, the boiling points increase as the number of electrons per molecule increases, which results in stronger van der Waals’ forces between the molecules. More energy is needed to overcome the van der Waals’ forces and separate the molecules.
What are the trends of water solubility within a homologous series?
If the functional group is able to interact with water, it will favour the solubility. However, the carbon skeleton is non-polar, and it does not help the solubility of the compound in water. Long carbon chains can counteract any solubility-favouring effect of the functional group, resulting in a decrease of solubility of carbon compounds of the same homologous series with increasing chain length.
What are the factors affecting the physical properties of a carbon compound?
The functional group it contains and the length of the carbon chain in the molecule.
Explain if haloalkanes with one halogen atom are polar.
Yes, because the carbon-halogen bond in the haloalkane is polar. Being a haloalkane with one halogen atom, the bond polarity cannot be cancelled and it remains as a polar molecule.
Explain if all haloalkanes are polar.
No, if the bond polarity of the carbon-halogen bonds are cancelled, as in tetrachloromethane, the molecule is non-polar.
Explain the trends of boiling points of haloalkanes.
The main type of intermolecular forces in haloalkanes are van der Waals’ forces.
As the carbon chain length increases, the strength of the van der Waals’ forces increase, and more heat is required to overcome these forces to boil the haloalkanes.
Similarly, the boiling points rise from each chloroalkane to the corresponding iodoalkane in the same position since larger molecules experience stronger van der Waals’ forces, and more heat is required to overcome these forces to boil the haloalkanes.
Explain the difference in boiling points between 1-chlorobutane and 2-chlorobutane.
1-chlorobutane has a higher boilng point than 2-chlorobutane. This is because its partial charged poles are further away from each other than that of 2-chlorobutane. This means that 1-chlorobutane is more polar than 2-chlorobutane, thus it has stronger van der Waals’ forces among its molecules. More heat is required to overcome these forces to boil 1-chlorobutane.
Explain the solubility of haloalkanes in water.
Haloalkanes are only very slightly soluble in water, since they cannot from hydrogen bonds with water molecules. The longer the carbon chain of the haloalkane, the less soluble it becomes.
Explain the trend of boiling points of alcohols.
The types of intermolecular forces in alcohols are hydrogen bonds and van der Waals’ forces.
As the carbon chain length increases, the strength of the van der Waals’ forces increase, and more heat is required to overcome these forces to boil the alcohols.
Explain the difference between the boiling points of alcohols and alkanes of similar relative molecular mass.
The boiling point of an alcohol is higher than that of an alkane with a similar relative molecular mass. This is because hydrogen bonds exist between alcohol molecules but not alkane molecules, while the only intermolecular forces between alkane molecules is van der Waals’ forces which are weaker than hydrogen bonds. Therefore, more heat is required to overcome these forces to boil the alcohols compared to the alkanes.
How many primary alcohols are infinitely soluble in water?
3 (methanol, ethanol, propan-1-ol)
What is the meaning of miscible?
Miscible means that two liquids can mix together in any proportion to form a single solution.
Explain the difference of solubility of hexan-1-ol and glucose in water.
Hexan-1-ol is insoluble in water but glucose is very soluble in water. Although glucose has a larger relative molecular mass, it has many more hydroxyl groups compared to hexan-1-ol, and it forms hydrogen bonds with water molecules more readily than hexan-1-ol. Therefore, glucose has a higher solubility in water.
Explain the trend of water solubility of primary alcohols of increasing chain length.
The alcohols with the shortest carbon chains are miscible with water in all proportions, because their molecules can form hydrogen bonds with water molecules. As the carbon chain length increases, the molecule becomes longer and the influence of the hydroxyl group becomes less important as it is attached to a long non-polar hydrocarbon tail. So, the water solubility of longer-chain alcohols decreases.
Do aldehydes need positional numbers for the location of the carbonyl group?
No, since it is always at the end of the carbon chain.
Explain if aldehydes and ketones are polar.
Yes, because the carbon-oxygen bond in the carbonyl group is polar.
Explain the major type of intermolecular forces among aldehyde and ketone molecules.
They have only van der Waals’ forces between their molecules. Although they have oxygen atoms with lone electrons in their carbonyl group, all their hydrogen atoms are joined to carbon atoms, thus are unavailable to form hydrogen bonds.
Explain the major type of intermolecular forces between aldehyde or ketone molecules, and water.
There is hydrogen bonding between aldehyde or ketone molecules and water. The lone pair of electrons of the partial negatively charged oxygen atom in the carbonyl group forms hydrogen bonds with the partial positive end of water molecules on the hydrogen atom.
Explain if the carboxyl group is polar.
Yes. Both the carbon-oxygen bond and the oxygen-hydrogen bond in the carboxyl group is polar, and their polarities do not cancel out each other, so the group is polar on the whole.
Explain the difference in boiling points of carboxylic acids and alcohols of a similar relative molecular mass.
The boiling point of the carboxylic acid is higher than that of an alcohol of similar relative molecular mass. This is because the hydrogen bonding between any two acid molecules leads to the formation of a dimer, which is very stable, and doubles the size of the molecule. This increases the van der Waals’ forces between the dimers, resulting in a higher boiling points.
Explain the difference in water solubility of carboxylic acids and alcohols with the same carbon chain length.
Carboxylic acids are more soluble in water than alcohols of the same carbon chain length. This is because molecules of carboxylic acid can form more hydrogen bonds with water molecules.
Explain the difference in boiling points of esters and alcohols of a similar relative molecular mass.
The boiling point of esters are lower than alcohols with similar relative molecular masses. This is because esters do not have hydrogen atoms available for hydrogen bonding, so there is no hydrogen bonding and only van der Waals’ forces among its molecules, unlike hydrogen bonding in alcohols.
Explain the major type of intermolecular forces between ester molecules and water.
There is hydrogen bonding between ester molecules and water. The lone pair of electrons of the partial negatively charged oxygen atom in the ester group forms hydrogen bonds with the partial positive end of water molecules on the hydrogen atom.
Do amides need positional numbers for the location of the amide group?
Unsubstituted amides do not, since the -NH2 group is always located at the end of the carbon chain. However, substituted amide groups may be located in the middle of the carbon chain and they require positional numbers in naming.
What is the major type of intermolecular forces among amide molecules?
There is extensive hydrogen bonding among amide molecules.
How many unsubstituted amides are soluble in water?
5 (carbon chain length ranging from 1 to 5)
Explain if amines are polar molecules.
Yes, since the carbon-nitrogen bond and carbon-hydrogen bonds in an amine molecule are polar.
What is the major type of intermolecular forces among amine molecules?
Hydrogen bonds
Explain the difference in boiling points of amines and alcohols of a similar relative molecular mass.
The boiling point of amines is lower than alcohols with a similar relative molecular mass. This is because nitrogen is less electronegative than oxygen, thus the nitrogen-hydrogen bond in amines is less polar than the oxygen-hydrogen bond in alcohols. As a result, the hydrogen bonds among amine molecules are weaker than that among alcohol molecules.
What is the common name of methanoic acid?
Formic acid
What is the IUPAC name of lactic acid?
2-hydroxypropanoic acid
Out of the 10 homologous series in the HKDSE syllabus, list all homologous series whose functional group can only be found at the end of the carbon chain.
Aldehydes and unsubstituted amides
Out of the 10 homologous series in the HKDSE syllabus, list all homologous series which undergoes hydrogen bonding among its own molecules.
Alcohols, carboxylic acids, unsubstituted amides, amines
Out of the 10 homologous series in the HKDSE syllabus, list all homologous series which undergoes hydrogen bonding with water molecules.
Alcohols, aldehydes, ketones, carboxylic acids, esters, unsubstituted amides, amines
