10th Class Chemistry Chapter 11 Organic Chemistry Complete Solved Exercise

Chemistry Notes

Chapter: Organic Chemistry

(Complete solved exercise + Self-assessment exercises)

Multiple Choice Questions:

Condensed structural formula for butane is

CH₃-CH₂-CH₃
CH₃-CH₂-CH₂-CH₃
CH₃-CH₂-CH₂-CH₂-CH₃
CH₃-CH₃

Solution:

Condensed structural formula for butane is CH₃-CH₂-CH₂-CH₃.

Therefore, the answer is b.

————————————————-

CH₃-CH₂-CH₃ is the chemical formula for:

Ethane
Propane
Butane
Pentane

Solution:

In CH₃-CH₂-CH₃ three carbon atoms are present.
For three carbon atom alkane’s prefix Prop- and suffix “ane” is used.
So, the chemical formula given above is the formula of propane.
Therefore, the answer is b.

————————————————-

Which compound is not saturated hydrocarbon?

CH₃-CH₃
CH₄
CH₃-CH=CH₂
CH₃-CH₂-CH₃

Solution:

The compounds in options a, b and d are saturated hydrocarbons.
Because they have only single covalent bond between carbon atoms.
They do not have double or triple covalent bond.
Therefore they all are saturated hydrocarbons according to saturated hydrocarbon’s definition.
While the compound in option c have one double covalent bond between last two carbon atoms.
This double covalent bond is the indication of un-saturated hydrocarbons.
Therefore the answer is c.

————————————————-

Stem “But” stands for how many carbon atoms

Solution:

But- is the stem(prefix) used for 4 carbon atoms.
Therefore the answer is 4.
The prefixes used for carbon atoms number 1 to 10 are listed in the table below.

Stem(Prefix)	Number of Carbon atoms
Meth-	1
Eth-	2
Prop-	3
But-	4
Pent-	5
Hex-	6
Hept-	7
Oct-	8
Non-	9
Dec-	10

————————————————-

Pitch is produced by

Coal
Coal tar
Coal gas
Petroleum

Solution:

Pitch is a waste material left behind after fractional distillation of coal.
This pitch is used in the construction of roads and roof of buildings.

————————————————-

The functional group –CO- is found in

Alcohols
Ketones
Carboxylic acids
Esters

Solution:

Ketones are derivatives of hydrocarbons that include a carbonyl functional group (-CO-), which replaces at least one hydrogen atom in the hydrocarbon.
Two alkyl groups are affixed to the carbonyl carbon in ketone molecules.
Therefore, the answer is ketones.

————————————————-

In which of the following compounds, oxygen is attached to two alkyl carbon atoms?

Alcohol
Phenol
Ether
Ester

Solution:

Ether is a derivative of a hydrocarbon in which the oxygen functional group -O- has been substituted for at least one H atom.
Therefore, in ethers, one alkyl group will be attached to oxygen from the left and the other alkyl group from the right.
Therefore, the answer is ether.

————————————————-

Which of the following is an alcohol?

CH₃-CH₂-O-CH₂-CH₃
CH₃-CH₂-COOH
C₆H₅-OH
CH₃-CH₂-OH

Solution:

Alcohols are hydrocarbon derivatives having at least one H atom changed to an -OH group.
One H replaceable -OH functional group is present in the molecule in option d.
Therefore, the answer is CH3-CH2-OH.

————————————————-

The functional group of amines is

–OH
–COOH
–NH₂
–CHO

Solution:

Amines are hydrocarbons that have at least one hydrogen atom replaced with an NH₂ group.
The amino functional group is present (-NH₂) in amines.
Therefore, the answer is –NH₂

————————————————-

Formic acid contains

–OH
–CO-
–COOH
–CHO

Solution:

Hydrocarbon derivatives called carboxylic acids have at least one H atom changed to a -COOH functional group.
Formic acid belongs to the family of carboxylic acids and has the functional group -COOH carboxyl.
Therefore, the answer is –COOH.

————————————————-

Give Short Answers:

What is catenation ?

Answer: Catenation:

The name catenation can be defined as the carbon’s capacity for self-linkage e.g.

CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Because of this catenation feature, organic compounds are abundant and can be found in a wide variety of forms.
On the basis of its catenation property, no other element can rival carbon
While some other elements, such as Si, Se, and S (e.g., S8), are also capable of forming chains, their capacity is constrained because they can only do so with short chains
As opposed to carbon atoms, which may form extraordinarily long chains
There might be thousands of carbon atoms, even in a single chain
Isomerism is second in importance to catenation in explaining the diversity of carbon compounds.

————————————————-

Define isomerism.

Answer: Isomerism:

The phenomenon of isomerism refers to organic compounds with the same molecular formula but a distinct structural formula as a result of a different atom arrangement inside molecules.

Example 1:

Explanation:

Keep an eye on the two chemical substances mentioned above
Their molecules share the same formula C₄H₁₀
Take note of how differently their structures are
The atoms’ varied arrangements explain why the structures differ
The isomer of normal butane is hence iso-butane

Example 2:

Explanation:

The three compounds listed above each have a unique structure
Total the number of atoms in each molecule
Their chemical formula, which may be determined by counting atoms, is C₅H₁₂
Normal pentane’s chemical composition is C₅H₁₂
As was said in the first example, a molecule’s structure can vary depending on how its atoms are arranged
The isomers of normal pentane are the other two structures, such as iso-pentane and neo-pentane

Note: The quantity of carbon atoms in a molecule determines how many isomers there are. There are more isomers as the carbon chain lengthens.

————————————————-

Give three examples of alkyl groups.

Answer:

Alkyl groups are saturated hydrocarbons, missing a single hydrogen atom
For example, Methane into methyl (CH₄ -> CH₃),
Ethane into ethyl (CH₃-CH₃-> CH₃CH₂),
Propane into propyl (CH₃CH₂CH₃->CH₃CH₂CH₂).

————————————————-

Define a functional group.

Answer: Functional Group:

A functional group can be defined as a single atom or a collection of atoms that describes a compound’s physical or chemical characteristics
Millions of chemical molecules can be studied sequentially thanks to functional groups
Due to this functional group, each family of organic compounds can be conveniently examined
For example, functional group of ketone is –CO-, functional group of amine is –NH₂, functional group of ether is –O- etc.

————————————————-

What is the difference between an alkane from an alkyl radical?

Answer:

Alkane and Alkyl Radicals:

Alkane:

Alkanes are hydrocarbons that include a single covalent bond holding two or more carbon atoms together or to a hydrogen atom in an open chain or close chain, as was previously explained.
There won’t be any double or triple covalent bonds in alkanes, only single covalent bonds. e.g.

Alkyl Radical:

When one hydrogen atom is removed from alkane then it results the formation of alkyl radical
For example; Methane produces methyl (radical) when one hydrogen atom removed from it
Ethane produces ethyl (radical) when one hydrogen atom removed from it
Propane produces propyl (radical) when one hydrogen atom removed from it, and so on.

For example:

Method to convert alkane into alkyl radical:

Compose the alkane’s member condensed formula
Dehydrogenate the compound by removing one hydrogen
Change the ending -ane in the alkane to -yl to give the radical a name
By removing hydrogen atom from the terminal carbon atom. Normal alkyl (radical) will be produced e.g.

By removing hydrogen atom from the second last carbon atom. Iso-alkyl (radical) will be produced e.g.

————————————————-

What do you mean by the term destructive distillation?

Answer: Destructive Distillation:

High temperature heating of coal produces coal gas, coal tar, and coke when oxygen is not present. And the term used for this procedure is coal destructive distillation.

————————————————-

List some general characteristics of organic compounds.

Answer: The following list of qualities for organic compounds:

Presence:

Both living and non-living things have the means to produce organic compounds

Covalent Bond:

Covalent bonds are the most frequent type of chemical connection made between organic substances (the bond formed by mutual sharing of electrons is called covalent bond)

Catenation:

Carbon, the cornerstone of organic molecules, has the ability to self-link
This potential for self-linking is regarded as the catenation property
Organic chemicals are widespread and come in lengthy chain forms because of this feature

Constituents:

Although carbon serves as the foundation for organic molecules, additional elements such as H, S, N, O, F, Cl, Br, I, and P etc. are also present.

Melting and Boiling Points:

Covalent bonds hold organic components together.
We are aware that covalent bonds alone are insufficiently strong.
Therefore, most organic compounds are volatile and have low melting and boiling temperatures due to bond fragility.
Bond strength is strongly correlated with melting and boiling points.
The melting and boiling points will be higher the stronger the relationship.
Lower melting and boiling points correspond to weaker bonds.

Solubility:

The chemical components that make up the hydrocarbons are non-polar in nature.
The small difference in electronegativity between carbon and hydrogen atoms is what causes the non-polar nature.
In contrast, hydrocarbon derivatives are both polar and organic in nature.
The difference in electronegativity between carbon and other atoms, such as O, N, S, P, F, Cl, Br, and I, is what causes their polarity.
Non-polar organic compounds are soluble in non-polar solvents like benzene, ether, carbon disulphide, and carbon tetrachloride, according to the “like dissolves like” rule.
While polar solvents like methanol and ethanol are used to dissolve polar organic molecules.

Similarity in Behavior (Homology):

Organic substances behave remarkably identical to one another.
They can be conveniently studied in a series known as a homologous series due to their similar behavior.
Organic compounds are organized in this series in order of increasing one -CH₂-group size.
If a compound has two -CH₂– groups, the preceding compound will have three, the after four, and so on.

Rate of Reaction:

Organic substances are less stable and have sluggish reaction rates because they have covalent bonds which are not so much strong in nature.

————————————————-

List major commercial sources of alkanes.

Answer: Organic Compounds’ Sources:

There are two primary sources of alkanes for commercial use.
One from Natural Sources
And the other from man-made ones (artificial sources).
Coal, natural gas, petroleum, and living things are examples of natural resources.
While researchers’ laboratory production of organic chemicals is the artificial source.
Coal:
The rich trove of organic chemicals is coal.
Another name for it is solid fuel.
Because it is solid and used as fuel.
Coal is dark in color

Destructive Distillation:

High temperature heating of coal produces coal gas, coal tar, and coke when oxygen is not present. And the term used for this procedure is coal destructive distillation.

Coal gas:
It’s not just one gas, but several.
However, it contains a combination of gases, including methane, hydrogen, and carbon monoxide.
Industrial uses of coal gas include fuel.
Coal Tar:
The wealth of organic molecules in coal tar is astounding.
However, it does include benzene and its derivatives.
Fractional distillation is a process that can be used to extract benzene and its compounds from coal tar.
The residue left behind after fractional distillation, which separates useful chemicals like benzene and its derivatives from coal tar, is also beneficial.
Pitch, the name of this residue, is used to make metal roadways and building roofs.
The manufacture of plastics, dyes, textiles, pharmaceuticals, paints, and varnishes, among other things, uses benzene and its derivatives, which are quite helpful.

Fractional Distillation:

Fractional distillation is the process of separating components of a solution based on the differences in their boiling points.

Natural Gas:
Natural gas is not just one type of gas.
It is a concoction of gases.
Methane, ethane, propane, and butane are just a few of the low-boiling hydrocarbons that it contains.
Methane, however, makes up a much larger portion of the mixture than the other gases do.
Petroleum:
The Latin words “petra” which means “rock,” and oleum, which means “oil,” combine to form the English word petroleum.
Thus, petroleum refers to rock oil as it is known to exist underground.
Dark brown in color, petroleum has a foul odour.
Petroleum is a mixture of several hydrocarbons.
However, it’s a blend of long chain hydrocarbons.
It contains aromatic hydrocarbons, cycloalkanes, and alkanes.
Additionally, there are minor amounts of S, O, and N, Ni, Cu, and V in petroleum.
Living Organisms:
The primary source of organic molecules is living things.
Due to the fact that both medications and carbohydrates are derived from plants (living organisms).
Animals (living beings) provide us with organic components like proteins and lipids.

ii): Artificial Source (men made):

Laboratory:

According to the records, mankind have created probably 10 million or more organic molecules in laboratories.
And the organic compounds that these men created are extremely beneficial and are sold as medicines for the treatment of fatal diseases like cancer, HIV, tuberculosis, and others.
Additionally, while producing dyes, plastics, paints, cosmetics, detergents, and fertilizers, along with other things.

————————————————-

Identify the following compounds on the basis of the functional groups they contain and encircle the functional groups.

Answer:

CH₃-CH=CH₂is an alkene. Its double bond functional group allows us to recognize it.
CH₃-CH₂-COOH is carboxylic acid. The presence of the carboxyl functional group, -COOH, in it allows us to recognize it.
Another carboxylic acid is CH₃-CO-OH. The presence of the carboxyl functional group, -COOH, in it allows us to recognize it.
The compound CH₃-CO-CH₃ is a ketone. Its carbonyl functional group –CO-, allows us to recognize it.
CH₃-CO-OCH₃ is an ester. It can be recognized by the ester functional group -COOR that is present in it.
HCOCH₃ is an acetaldehyde. It can be recognized by the presence of the aldehyde functional group -COH.

——————————

What is the name of the alkane having seven carbon atoms in the chain?

Answer:

We are aware that the prefix “hept-” is used for seven carbon atoms, and the suffix “ane” is used for alkane.
Now we shall write the prefix hept- followed by the suffix “ane.”
Heptane will thus be the name given to the compound with seven carbon atoms.

————————————————-

What is the name of the alkyl group obtained by removing an end hydrogen atom from i) propane or ii) ethane?

Answer:

We know that an alkyl radical is produced when a single hydrogen atom is removed from an alkane.
Therefore, if we take one hydrogen atom out of propane, propyl will result.
While ethyl is produced when we take one hydrogen atom out of ethane.
Propane -> Propyl (CH₃CH₂CH₃-> CH₃CH₂CH₂)
Ethane -> Ethyl (CH₃CH₃->CH₃CH₂)

————————————————-

Give the structural formula of two alkanes and one alkyne.

Answer: The structural formulas of two simple alkanes are:

The structural formula of a simple alkyne is:

————————————————-

What is meant by the term “functional group” ?

Answer: Functional Group:

A functional group is a single atom or a collection of atoms that describes a compound’s physical or chemical characteristics
Millions of chemical molecules can be studied sequentially thanks to functional groups
Due to this functional group, each family of organic compounds can be conveniently examined

On the basis of functional group organic compounds are classified as:

Hydrocarbons
Derivatives of Hydrocarbons

1): Hydrocarbons:

Since only carbon and hydrogen atoms are found in organic substances, hydrocarbons are known as such.
They could have a ring structure or an open chain structure.

Alkanes:

Alkanes, also known as saturated hydrocarbons, are hydrocarbons in which all of the carbon atoms are connected by a single covalent bond, either in a straight chain structure or a ring shape.
There won’t be any double or triple covalent bonds in saturated hydrocarbons, only single covalent bonds.

Alkenes:

Alkenes, also known as “unsaturated hydrocarbons,” are hydrocarbons in which at least two carbon atoms are connected together by a double covalent bond.

Alkynes:

Alkynes, as well known as “unsaturated hydrocarbons” are hydrocarbons in which at least two carbon atoms are linked together by a triple covalent bond.

2): Derivatives of Hydrocarbons:

We can infer that hydrocarbons of any open-chain or close chain hydrocarbons in which at least one hydrogen atom has been substituted with a heteroatom, such as N, O, S, or Cl are called derivatives of hydrocarbons.
Methane is the first alkane in the homologous series (CH₄).
A simple hydrocarbon is methane.
By substituting other atoms for its one hydrogen atom, such as OH, Cl, Br, NH₂, and CN, we can create its derivatives. For example

CH₄, CH₃-OH, CH₃-Cl, CH₃-Br, CH₃-NH₂, CH₃-CN etc.

Derivatives of hydrocarbons are described in depth in the table below.

According to their functional groups, organic compounds are categorized in the following table:

Brief Detail of Functional Groups given in above Table:

Alkanes:

Alkanes are hydrocarbons that include a single covalent bond holding two or more carbon atoms together or with a hydrogen atom in an open chain or close chain.
There won’t be any double or triple covalent bonds in alkanes, only single covalent bonds
For example; CH₄, CH₃-CH₃, CH₃-CH₂-CH₂-CH₃ etc.

Alkenes:

Alkenes are hydrocarbons that have at least two carbon atoms bound by a double covalent bond, either in a straight chain or a close chain
For example; CH₂=CH₂, CH₃-CH=CH-CH₃etc.

Alkynes:

Alkynes are hydrocarbons that contain three triple covalent bonds connecting at least two carbon atoms e.g.

Alkyl Halide:

Alkyl halides are hydrocarbons that have at least one hydrogen atom replaced to one of the halogen atoms F, Cl, Br, or I.
Halo functional group is present in them (-X)
For example; CH₃-Cl, CH₃-Br, CH₃-F, CH₃-I, CH₃-CH₂-CH₂-Cl, CH₃-CH₂-CH₂-F, CH₃-CH₂-CH₂-CH₂-CH₂-Br etc.

For understanding consider methyl chloride (CH₃-Cl):

We are aware that carbon form four covalent connections to attain stability.
This demonstrates how the carbon atom in chloromethane fulfils its valency by creating three covalent bonds with hydrogen atoms and one covalent bond with any halogen atom (replaced with hydrogen atom).

Alcohol:

Alcohols are hydrocarbons that have at least one hydrogen atom replaced with an OH group.
They have a hydroxyl functional group (-OH).
For example; CH₃-OH, CH₃-CH₂-OH, CH₃-CH₂-CH₂-CH₂-CH₂-OH etc. are open chain alcohols.
Even though when –OH group is attached to benzene ring the it is called phenol e.g.

For understanding consider methanol (CH₃-OH):

We are aware that the carbon atom forms four covalent connections to attain stability.
In the case of open chain alcohols, the carbon atom in methanol is fulfilling its valency by creating three covalent bonds with hydrogen atoms and one covalent bond with the OH group (replaced with hydrogen atom).
While in phenol carbon number 1 making three covalent bonds with two more carbon atoms (carbon number 2 and 6) and one covalent bond with an OH group (replaced with hydrogen atom).
Therefore, like methanol phenol also fulfils its valency.

Amines:

Amines are hydrocarbons that have at least one hydrogen atom replaced with an NH₂ group.
The amino functional group is present (-NH2) in amines. .
For example CH₃-NH₂, CH₃-CH₂-NH₂, CH₃-CH₂-CH₂-CH₂-CH₂-NH₂ etc. are open chain amines.
Even though aniline is an aromatic amine e.g.

For understanding consider methyl amine (CH₃-NH₂) and aniline:

We are aware that the carbon atom forms four covalent connections to attain stability.
In this example of an open chain amine, the carbon atom is fulfilling its valency by creating three covalent bonds with hydrogen atoms and one covalent bond with the NH₂ group (replaced with hydrogen atom).
In aromatic amine, such as aniline, carbon number 1 additionally fulfils its valency by creating three covalent bonds with two other carbon atoms (carbon number 2 and 6), one covalent bond with the NH₂ group (replaced with hydrogen atom).

Ethers:

Ethers are hydrocarbons that have at least one hydrogen atom substituted with an O-R group.
The oxygen functional group is present (-O-) in ethers
For example; CH₃-O-CH₃, CH₃-CH₂-O-CH₃, CH₃-CH₂-CH₂-CH₂-CH₂-O-CH₂-CH₃ etc.

For understanding consider dimethyl ether (CH₃-O-CH₃):

We are aware that the carbon atom forms four covalent connections to attain stability.
Here, we can observe that the left and right carbons in dimethyl ether are both satisfying the valency of the compound by creating three covalent bonds with hydrogen atoms and one covalent bond with an oxygen atom (replaced with hydrogen atom).

Ketones:

Ketones are derivatives of hydrocarbons that include a carbonyl functional group (-COR), which replaces at least one hydrogen atom in the hydrocarbon.
Two alkyl groups are affixed to the carbonyl carbon in ketone molecules.
For example; CH₃-CO-CH₃, CH₃-CH₂-CO-CH₃, CH₃-CH₂-CH₂-CH₂-CH₂-CO-CH₃ etc.

Aldehydes:

Aldehydes are derivatives of hydrocarbons that have at least one hydrogen atom removed in favor of a carbonyl functional group (-COH).
Aldehydes are compounds made of carbonyl carbon and one or two hydrogen atoms attached to that carbonyl carbon atom
For example; H-CO-H, CH₃-CO-H, CH₃-CH₂-CO-H, CH₃-CH₂-CH₂-CH₂-CH₂-CO-H etc.

Carboxylic acids:

Carboxylic acids are derivatives of hydrocarbons that have a carboxyl functional group in place of at least one hydrogen atom, also known as the -COOH group
For example; CH₃-CO-OH, CH₃-CH₂-CO-OH, CH₃-CH₂-CH₂-CH₂-CH₂-CO-OH etc.

Acid Halides:

Acid halides are derivatives of hydrocarbons that have an acyl group (-CO-X) with at least one hydrogen atom substituted by a COX group
For example; CH₃-CO-Cl, CH₃-CH₂-CO-Br, CH₃-CH₂-CH₂-CH₂-CH₂-CO-Cl etc.

Acid Amides:

Acid amides are derivatives of hydrocarbons that have at least one hydrogen atom replaced with a CO-NH₂ group.
The amide functional group (-CO-NH₂) is present in acid amides
For example; CH₃-CO-NH₂, CH₃-CH₂-CO-NH₂, CH₃-CH₂-CH₂-CH₂-CH₂-CO-NH₂ etc.

Esters:

Esters are derivatives of hydrocarbons that have at least one hydrogen atom replaced with a COOR group.
They have ester functional group (-COOR) in them
For example; CH₃-CO-OCH₃, CH₃-CH₂-CO-OCH₃, CH₃-CH₂-CH₂-CH₂-CH₂-CO-OCH₃ etc.

Alkyl Cyanide:

Alkyl cyanides are hydrocarbons that have at least one hydrogen atom substituted with a CN group.
They have “cyano” functional group (-CN) in them
For example; CH₃-CN, CH₃-CH₂-CN, CH₃-CH₂-CH₂-CH₂-CH₂-CN etc.

————————————————-

Identify the type of the following compounds as alcohol, aldehyde, or ketone?

(a) HCHO, an ingredient in the production of polymers like urotropine, a drug used to treat urinary tract infections.

b) The nail polish remover ingredient CH₃COCH₃.

c) CH₃CH₂OH, which is a key ingredient in the creation of numerous organic products like tinctures, cosmetics, and polymers.

Answer:

HCHO is aldehyde. We can identify it by aldehyde functional group –COH present in it.
CH₃COCH₃ is a ketone. We can identify it by ketone functional group (carbonyl –CO-) present in it.
CH₃-CH₂OH is alcohol. We can identify it by alcohol functional group –OH present in it.

————————————————-

Think-Tank

Give a molecular formula of a compound containing C, H and O and single bonds. List all the possible functional groups this compound have?

Answer: If a compound contains only C, H and O then the possible functional group it may have will be.

It may be alcohol CH₃OH. As we know that alcohols can be identified by hydroxyl functional group –OH.
It may be ether CH₃-O-CH₃. As we know that ethers can be identified by oxygen functional group –O- .

————————————————-

Give the condensed structural formulas of the following compounds and classify each on basis of functional group.

Answer:

It is an alcohol. We can identify it by alcohol functional group –OH present in it. The condensed structural formula for this propanol is CH₃CH₂CH₂OH.
It is an ether. We can identify it by ether functional group –O- present in it. The condensed structural formula for this dimethyl ether is CH₃OCH₃.

————————————————-

The diagram represents an organic compound that contains three different elements.

What could be the compound?

Ethanoic acid
Propene
Ethanol
Propane

Answer:

The compound given above in the structure is alcohol.
In the structure the X showing hydrogen atoms.
The Y showing carbon atoms.
The Z showing oxygen atom.
We can draw the exact structure as:

————————————————-

Polyvinyl chloride (PVC) is a polymer. It is used for making vinyl sheets, drainage pipes, wire insulation etc. It is obtained from vinyl chloride.

Classify vinyl chloride as saturated or un-saturated compound.

Answer: Vinyl Chloride:

Vinyl chloride is un-saturated compound.
We can identify it by double covalent bond present between two carbon atoms.
As we know that saturated compounds are those, which have at least one double or triple covalent bond between two carbon atoms.

————————————————-

For each of the following, draw the structural formulas of a two-carbon compound containing the indicated functional group.

Alcohol
Aldehyde
Carboxylic acid
Alkene

Answer:

Alcohol:

Structural formula for two-carbon alcohol is given below:

Aldehyde:

Structural formula for two-carbon aldehyde is given below:

Carboxylic acid:

Structural formula for two-carbon carboxylic acid is:

Alkene:

Structural formula for two carbon alkene is:

————————————————-

Aspirin is a mild pain killer and fever reducer; it is manufactured from salicylic acid.

Identify functional groups present in it and encircle them.

Answer:

In aspirin two functional groups are present.
One functional group is carboxyl functional group –COOH and the second functional group is hydroxyl functional group –OH.
The carboxyl functional group is the functional group, gives the identification carboxylic acids and the hydroxyl functional group is the functional group, gives the identification of alcohols.

————————————————-

General formula for Alkane is C_nH_2n+2. What will be the general formula for alkyl radical?

Answer:

For alkyl radicals the general formula is C_nH_2n+1
n is the number of carbon atoms and it is n = 1, 2, 3…………….
If we have one carbon atom then according to formula C₁H_2×1+1= C₁H₂₊₁= C₁H₃ = CH₃ is methyl.
Same for the 2, 3, 4 carbons atoms and so on.

————————————————-

Water adds to ethene according to the following reactions:

Identify functional groups in the reactant and product molecules.

Answer:

We can see from the aforementioned reaction that the reactant located on the left side is an alkene.
The double bond that exists between two carbon atoms allowed us to identify it.
As is common knowledge, alkenes are organic compounds in which any two carbon atoms will form at least one double covalent bond.
As a result, when an alkene reacts with water, alcohol is produced on the reaction’s right side.
The presence of the hydroxyl functional group -OH in alcohol allowed us to identify it.
As far as we are aware, alcohol is any organic substance in which hydroxyl -OH group is replaced with at least one hydrogen atom.

————————————————-

Bonding of carbon atom to heteroatoms increases the number of organic compounds. Justify it.

Answer:

We’ll use a straightforward example to illustrate how adding one digit to a group of digits increases the number of numbers.

Let’s use the saturated hydrocarbon butane (CH3-CH2-CH2-CH3) as an example to ensure complete pleasure Now, if we add an oxygen atom to this butane, we will have the following three new compounds:

CH₃-CH₂-CH₂-CH₂-OH (Butanol)
CH₃-CH₂-O-CH₂-CH₃ (Diethyl ether)
CH₃-CH₂-CH₂-O-CH₃ (Methyl propyl ether)

Therefore, in this way the number of organic compounds increases with the bonding of heteroatoms to carbon atom.

————————————————-

Self-evaluation problem 11.1:

Give the molecular, structural and condensed structural formulas for

Butane
Hexane
Octane

Answer:

Butane:

Molecular formula:

C₄H₁₀

Condensed structural formula:

CH₃CH₂CH₂CH₃

Hexane:

Molecular formula:

C₆H₁₄

Condensed structural formula:

CH₃CH₂CH₂CH₂CH₂CH₃

Octane:

Molecular formula:

C₈H₁₈

Condensed structural formula:

CH₃CH₂CH₂CH₂CH₂CH₂CH₂CH₃

Self-evaluation problem 11.2:

Choose the saturated and unsaturated compounds from the following.

Answer:

Compound (i) have only single covalent bonds between carbon atoms. Therefore it is saturated compound. As we know that saturated compounds are those which have only single covalent bonds between carbon atoms, not double or triple covalent bonds.
Compound (ii) have triple covalent bonds between last two carbon atoms. Therefore it is un-saturated compound. As we know that un-saturated compounds are those compounds in which at least one double or triple covalent bond is present between any of two carbon atoms.
Compound (iii) have double covalent bonds between last two carbon atoms. Therefore it is un-saturated compound. As we know that un-saturated compounds are those compounds in which at least one double or triple covalent bond is present between any of two carbon atoms.
Compound (iv) have two double covalent bonds between first two carbon atoms and last two carbon atoms. Therefore, it is un-saturated compound. As we know that un-saturated compounds are those compounds in which at least one double bond or triple bond is present between any of two carbon atoms.

Self-evaluation problem 11.3:

Write IUPAC names of the following alkanes.

CH₃-CH₂-CH₂-CH₂-CH₂-CH₃
CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃
CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃
CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃
CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Answer:

CH₃-CH₂-CH₂-CH₂-CH₂-CH₃

Verify the prefix in the table for six carbon atom
Prefix for six carbon atom is Hex-
Verify each bond in a compound
When the compounds only have one type of covalent bond (single covalent bond). Consequently, the compound is an alkane
The alkane family’s suffix is “ane”
We’ll write the prefix first, then the suffix
Therefore, the IUPAC name of the compound will be Hexane

2.CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Verify the prefix in the table for eight carbon atom
Prefix for eight carbon atom is Oct-
Verify each bond in a compound
When the compounds only have one type of covalent bond (single covalent bond). Consequently, the compound is an alkane
The alkane family’s suffix is “ane”
We’ll write the prefix first, then the suffix
Therefore, the IUPAC name of the compound will be Octane

3. CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Verify the prefix in the table for seven carbon atom
Prefix for seven carbon atom is Hept-
Verify each bond in a compound
When the compounds only have one type of covalent bond (single covalent bond). Consequently, the compound is an alkane
The alkane family’s suffix is “ane”
We’ll write the prefix first, then the suffix
Therefore, the IUPAC name of the compound will be Heptane

4. CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Verify the prefix in the table for ten carbon atom
Prefix for ten carbon atom is Dec-
Verify each bond in a compound
When the compounds only have one type of covalent bond (single covalent bond). Consequently, the compound is an alkane
The alkane family’s suffix is “ane”
We’ll write the prefix first, then the suffix
Therefore, the IUPAC name of the compound will be Decane

5. CH₃-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₂-CH₃

Verify the prefix in the table for nine carbon atom
Prefix for nine carbon atom is Non-
Verify each bond in a compound
When the compounds only have one type of covalent bond (single covalent bond). Consequently, the compound is an alkane
The alkane family’s suffix is “ane”
We’ll write the prefix first, then the suffix
Therefore, the IUPAC name of the compound will be Nonane

Self-evaluation problem 11.4

List the names of major sources of alkanes.
What is natural gas.
Write some uses of acetylene.

Answer:

Major sources of alkane are;

Coal
Natural gas
Petroleum
Living organisms
Synthesis in laboratory

5): Natural Gas:

Natural gas is not just one type of gas.
It is a concoction of gases.
Methane, ethane, propane, and butane are just a few of the low-boiling hydrocarbons that it contains.
Methane, however, makes up a much larger portion of the mixture than the other gases do.

6): Uses of acetylene:

Acetylene is used for ripening of food artificially and its flame called oxy-acetylene flame is used for cutting and welding of metals.

Self-evaluation problem 11.5:

Derive alkyl radicals from the following alkanes.

Ethane
Butane
Propane

Answer:

Ethane:

CH₃CH₃ (ethane) -> CH₃CH₂ (ethyl)

Butane:

CH₃CH₂CH₂CH₃ (Butane) -> CH₃CH₂CH₂CH₂ (Butyl)

Propane:

CH₃CH₂CH₃(Propane) -> CH₃CH₂CH₂ (Propyl)

Self-evaluation problem 11.6:

A to E are the structural formulae of some organic compounds.

Give the letters which represents:

Branched chain compounds
Cyclic compounds
Straight chain compounds

Answer:

Branched chain compounds:

D and E are branched chain compounds. We can see in compound D, hydroxyl functional group is branched to carbon number two, while in compound E, CH₃ group is branched to carbon number two.

Cyclic compound:

C is cyclic compound as we can see that all the carbon atoms are arranged in cyclic manner.

Straight chain compounds:

A, and B are straight chain compounds as we can see that all the carbon atoms are arranged in a straight chain manner.

Self-evaluation problem 11.7:

Classify the following compounds as alcohol, ether or phenol.

CH₃-CH₂-O-CH₂-CH₃
CH₃-CH₂-CH₂-OH
C₆H₅OH
C₂H₅OH

Answer:

CH₃-CH₂-O-CH₂-CH₃ is an ether. Its presence with the oxygen functional group -O- allows us to identify it. As far as we are aware, ethers are organic compounds in which at least one hydrogen atom has been replaced by an oxygen functional group (-O-).
CH₃-CH₂-CH₂-OH is an alcohol. The presence of the hydroxyl functional group -OH helps us to identify it. As is common knowledge, alcohols are organic compounds that have at least one hydrogen atom substituted with an -OH functional group.
C₆H₅OH is phenol. Its phenyl C₆H₅ and hydroxyl groups –OH allow us to identify it. As is common knowledge, phenols are chemical compounds with an -OH group connected to a phenyl group.

Self-evaluation problem 11.8:

Identify the following compounds as an aldehyde, or a ketone, or a carboxylic acid.

Answer:

Compound (a) is ketone. Its carbonyl functional group, CO, makes it easy to identify. As is common knowledge, organic molecules with a carbonyl -CO- functional group are known as ketones.
Compound (b) is an aldehyde. Its aldehyde functional group –COH, makes it easy to identify. As is common knowledge, organic compounds with an aldehyde –COH functional group are known as aldehydes.
The substance (c) is a carboxylic acid. Its carboxyl functional group –COOH, makes it easy to identify. As is common knowledge, organic molecules with a carboxyl functional group are known as ketones.

Activity 11.1

Differentiate between saturated and unsaturated compounds using, iodine bromine and potassium permanganate.

Solution:

5 cm³ of carbon tetrachloride should be used to dissolve 2-3 cm³ of mustard oil. Three pieces make up this solution. Shake a portion of it after adding a few drops of bromine water.
Shake after adding a few drops of iodine solution to the second portion.
Shake (Bayer’s test) the third component after adding a few drops of diluted alkaline KMnO₄ solution.
With kerosene oil, repeat these three processes.
Unsaturated chemicals are released, giving off the colors; reddish brown of bromine water, purple of iodine solution, and purple of the alkaline KMnO₄.
These assays are not applicable to saturated substances.

Activity 11.2

Identifying carboxylic acids, phenols, amines, aldehydes, and ketones in terms of functional groups.

Solution:

To recognize the functional groups experimentally, execute the following.

Examine for carboxylic acids:

Vinegar-dipped blue litmus paper is used.
The presence of carboxylic acid can be detected when the blue litmus paper becomes red.
Phenol testing:
In a test tube, mix 5 cm³ of water with a pinch of carbolic acid (phenol).
Fill it with bromine water.
This bromine water will produce a white precipitate when phenol is present, and this white precipitate is a sign that phenol is present.
Test for amine:
Heat a small amount of amine in a 2 cm³ alcoholic solution of potassium hydroxide and 0.5 cm³ of chloroform.
The smell from an amine is very offensive.
Additionally, the presence of the amine functional group is indicated by this offensive odour.
Tests for phenol :
5 cm³ of water and a teaspoon of carbolic acid (phenol) should be dissolved in a test tube.
Pour in some bromine water.
With this bromine water, phenol will produce a white precipitate, which is a sign that phenol is present.
Test for amine:
Heat a small amount of amine in a 2 cm³ alcoholic KOH solution with 0.5 cm³ of chloroform.
A strong, nasty smell will come from an amine.
And this offensive smell is a sign that an amine functional group is present.
Aldehyde test:
In a test tube, combine identical amounts of Fehling solutions A and B.
It should then be boiled for a while with a teaspoon of glucose added.
The presence of an aldehyde functional group is shown by the red precipitate that forms when Fehling solution is used.
Ketone testing:
Put a few drops of NaOH solution and 2-3 cm³ of sodium nitro-prusside solution in a test tube.
Acetone 1 cm³ should be added.
The presence of ketones is indicated by the appearance of red color