chapter organic chemistry

Class 10 Chemistry Chapter Organic Chemistry important Questions

Class 10 Chemistry Notes

Chapter Organic Chemistry important Questions

Answer the Following Questions:

  1. What does catenation mean?

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 .

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2.Clarify isomerism. Give a few instances.

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:

n-butane and iso-butane
isomers of butane

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:

n-pentane iso-pentane and neo-pentane
Pentane isomers

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.

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3.Provide three illustrations 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).

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4. 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.

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5. What distinguishes 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.
methane and ethane structural formulas
Types of alkane

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:

formation of alkyl radical
How alkyl radicals are formed

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.

propane to propyl radical formation
formation of propyl from propane

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6. What exactly do you mean by 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.

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7. List a few fundamental characteristics of organic substances.

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.

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8. 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.
  1. 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.

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9. Based on the functional groups they include, name the following substances and highlight the functional groups.

identify the organic compounds
Organic compounds

      Answer:

identify functional groups in following compounds
Functional groups identification
  1. CH3-CH=CH2 is an alkene. Its double bond functional group allows us to recognize it.
  2. CH3-CH2-COOH is carboxylic acid. The presence of the carboxyl functional group, -COOH, in it allows us to recognize it.
  3. Another carboxylic acid is CH3-CO-OH. The presence of the carboxyl functional group, -COOH, in it allows us to recognize it.
  4. The compound CH3-CO-CH3 is a ketone. Its carbonyl functional group –CO-, allows us to recognize it.
  5. CH3-CO-OCH3 is an ester. It can be recognized by the ester functional group -COOR that is present in it.
  6. HCOCH3 is an acetaldehyde. It can be recognized by the presence of the aldehyde functional group -COH.

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10. What is the name of the chained alkane with seven carbon atoms?

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.

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11. What is the name of the alkyl group created when an end hydrogen atom is taken out of either i) propane or ii) ethane?

     Answer:

  • We are aware 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)

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12. Describe the two straightforward alkanes and one alkyne structural formula.

Answer: The structural formulas of two simple alkanes are:

name first two alkanes
first two alkanes

The structural formula of a simple alkyne is:

acetylene
first simplest alkyne

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13. What does the word “functional group” mean? Describe in detail.

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:

  1. Hydrocarbons
  2. 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.
how hydrocarbons are classified
hydrocarbons

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:

Table containing functional groups of organic compounds:

functional groups
some common functional groups

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.
simplest alkanes
First 2 alkanes

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-CH3      etc.

Alkynes:

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

alkynes examples

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.
phenol structure

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.
aniline structure

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.

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14. Which of the following substances is an 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:

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

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15. Provide the molecular formula for a compound with single bonds and the elements C, H, and O. List every functional group that this chemical might contain.

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

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

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16. Give each of the following compounds’ condensed structural formulae and organize them according to their functional groups.

 Answer:

  1. 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.
  2. 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.

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17. The illustration depicts an organic complex made up of three distinct constituents.

identify organic compound

Choose the appropriate compound from the list below.

  1. Ethanoic acid
  2. Propene
  3. Ethanol
  4. 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:
ethanol

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18. PVC, or polyvinyl chloride, is a type of polymer. It is employed in the production of wire insulation, drainage pipes, and vinyl sheets. Vinyl chloride is used to make it.

Label the chemical vinyl chloride as saturated or un-saturated.

 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.

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19. Draw the structural formulae of a two-carbon molecule having each of the following functional groups for each of the following.

  1. Alcohol
  2. Aldehyde
  3. Carboxylic acid
  4. Alkene

       Answer:

Alcohol:

Structural formula for two-carbon alcohol is given below:

ethanol

Aldehyde:

Structural formula for two-carbon aldehyde is given below:

Carboxylic acid:

Structural formula for two-carbon carboxylic acid is:

acetic acid

Alkene:

Structural formula for two carbon alkene is:

ethene

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20. Aspirin is a non-addictive pain reliever and fever lower. It is produced using salicylic acid.

Choose and the functional groups that are present there. Justify the choice you made.

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.

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21. Alkane’s general formula is CnH2n+2. Create the alkyl radical’s general formula??

Answer:

  • For alkyl radicals the general formula is CnH2n+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 C1H2×1+1 = C1H2+1 = C1H3 = CH3 is methyl.
  • Same for the 2, 3, 4 carbons atoms and so on.

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22. Ethane reacts with water in the manner shown in the following response.

In the molecules of the reactant and product, compare the functional groups.

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.

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23. The number of organic compounds grows when carbon atoms bond to heteroatoms. Defend 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:

  1. CH3-CH2-CH2-CH2-OH (Butanol)
  2. CH3-CH2-O-CH2-CH3 (Diethyl ether)
  3. 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.

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24. List a few applications for organic compounds.

Answer:

Applications of organic compounds:

  1. As a Fuel:
  2. Natural gas, petroleum, and coal are examples of organic fuels that can be burned to generate heat.
  3. The gases that can be made from natural gas are propane and butane.
  4. Additionally, these gases are employed in fuel cylinders as a liquid.
  5. As a raw material for the synthesis of organic products:
  6. Coal, natural gas, petroleum are used a raw material for the synthesis of organic compounds.
  7. Ethylene is used as raw material for the synthesis of plastic (polyethylene), alcohol (ethanol), Carboxylic acid (acetic acid), and antifreeze (ethylene glycol).
  8. For the production of soap, medicines, cosmetics, detergents, emulsions, and other organic products, numerous different organic compounds are employed as raw ingredients.
  9. Synthesis of polymers:

Acetylene is utilized as a starting ingredient in the manufacture of polymers like nylon, rubber, and polyvinyl chloride (PVC).

  • For welding and cutting of metals:

Metals are chopped and joined together using an oxygen-acetylene flame.

  • For artificial ripening of food:

Artificial food ripening is accomplished using acetylene.

  • As an Antiseptic:

Phenol is a common antiseptic used in hospitals.

  • As a Solvent:

Methanol and ethanol are utilized in several reactions as well as solvents for fats, oils, paints and varnishes.

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25. Distinguish the various chemical compounds listed below based on the functional group.

  • CH3CH2OCH2CH3
  • C6H5OH
  • CH3OH
  • CH3COCH3
  • CH3CH2CHO
  • CH3COOH

Answer:

  1. CH3CH2OCH2CH3 is an ether. We can recognize it by oxygen functional group –O-. As we know that ethers contains oxygen functional group –O-.
  2. C6H5OH is phenol. We can recognize it by the phenyl group C6H5OH and by alcohol functional group –OH.
  3. CH3OH is alcohol. We can recognize it by hydroxyl functional group –OH. As we know that alcohols contain hydroxyl functional group –OH.
  4. CH3COCH3 is ketone. We can recognize it by carbonyl functional group –CO-. As we know that ketones contain carbonyl functional group –CO-.
  5. CH3CH2CHO is aldehyde functional group. We can recognize it by aldehyde functional group –COH. As we know that aldehydes contain –COH functional group.
  6. CH3COOH is carboxylic acid. We can recognize it by carboxyl functional group –COOH. As we know that carboxylic acids contain carboxyl functional group –COOH.

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26. Write the names of the following organic compounds in IUPAC nomenclature.

  • CH3CH2CH2CH2CH2CH3
  • CH3CH3
  • CH4

      Answer:

a):CH3CH2CH2CH2CH2CH3

  • 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

b): CH3CH3

  • Verify the prefix in the table for two carbon atom
  • Prefix for two carbon atom is Eth-
  • 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 Ethane

c): CH4

  • Verify the prefix in the table above for one carbon atom
  • Prefix for one carbon atom is Meth-
  • 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 Methane

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27. State pentane’s molecular, structural, and condensed structural formulas.

Answer:

Molecular Formula:

C5H12

(Pentane)

Molecular formula

Structural formula:

Condensed structural formula:

CH3CH2CH2CH2CH3

(Pentane)

Condensed structural formula

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28. Define Hydrocarbon.

Answer: Definition:

Organic compounds, composed of only carbon and hydrogen atoms are called hydrocarbons e.g.

CH4 (Methane), CH3CH3 (Ethane), CH3CH2CH3 (Propane)

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29. Compare and contrast saturated and unsaturated hydrocarbons.

Answer:

Saturated Hydrocarbons:

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. 

Unsaturated Hydrocarbons:

Alkenes:

  • Alkenes, also known as “unsaturated hydrocarbons,” are hydrocarbons in which at least two carbon atoms are connected together through 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.
pentane pentene and pentyne

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30. Explain how open chain and close chain hydrocarbons differ.

Answer: a): Open Chain/ Acyclic Organic Compounds:

  • The carbon atoms in these compounds are grouped in open chain form by covalent bonds, as the title implies.
  • Additionally, the chain of carbon atoms connected by a covalent bond might be straight or branched, for example.

b): Closed chain / Cyclic Compounds:

  • As the name suggests, these compounds’ carbon atoms are ordered in closed-chain form, and the carbons are connected together by covalent bond.
  • Or we could say that the carbon atoms in these compounds are structured in cycle form, through covalent bond for example.
  • Another idea is that an organic compound is considered to be homo-cyclic if the ring exclusively contains carbon atoms.
  • As the term homo means “same,” it follows that all of the carbon atoms in the ring are identical to one another, which is why it is called a homo-cyclic compound.
  • While hetero means “different” and means that there are not all carbon atoms in the ring
  • While the non-carbon atom is also present in the ring
  • In this way carbon and non-carbon atoms are not the same but different for each other
  • That’s why called heterocyclic, if the ring contains one non-carbon atom e.g. N, O, S, Cl etc.
what are homocyclic organic compounds
what are heterocyclic organic compounds

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31. Which organic substance is utilized in hospitals as an antiseptic?

Answer: Phenol C6H5 is an organic compound and used as an antiseptic in hospitals.

phenol diagram

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32. Which organic substance is used to ripen food artificially?

Answer: Acetylene is an organic compound used for the artificial ripening of food.

structure of acetylene

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33. Which organic substance is utilized to cut and weld metals?

Answer: Oxy-acetylene flame is used for cutting and welding of metals.

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Numerical Problems:

Self-evaluation problem 11.1:

  1. Provide the molecular, structural and condensed structural formulas for
  2. Butane
  3. Hexane
  4. 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:

  • From the list below, pick saturated and unsaturated chemicals.
identify saturated and unsaturated organic compounds

Answer:

  • Compound (i) have only single covalent bonds between carbon atoms. Therefore it is a 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) has triple covalent bonds between the last two carbon atoms. Therefore it is an unsaturated 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) has double covalent bonds between the last two carbon atoms. Therefore it is an unsaturated 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) has two double covalent bonds between the first two carbon atoms and last two carbon atoms. Therefore, it is an unsaturated 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:

  1. List the IUPAC names of these alkanes.
  2. CH3-CH2-CH2-CH2-CH2-CH3
  3. CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3
  4. CH3-CH2-CH2-CH2-CH2-CH2-CH3
  5. CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
  6. CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

Answer:

  1. CH3-CH2-CH2-CH2-CH2-CH3
  • Verify the prefix in the table for six carbon atom
  • Prefix for six carbon atoms 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 atoms 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 atoms 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 atoms 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 atoms 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:

  • Name the principal sources of alkanes.
  • Describe natural gas.
  • Describe some acetylene usage.

Answer:

a) Major sources of alkane are;

  1. Coal
  2. Natural gas
  3. Petroleum
  4. Living organisms
  5. Synthesis in laboratory

b) 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.

c) Uses of acetylene:

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

Self-evaluation problem 11.5:

  • Use the following alkanes to produce alkyl radicals.
  • Ethane
  • Butane
  • Propane

Answer:

Ethane:

CH3CH3 (ethane) ->CH3CH2 (ethyl)

Butane:

CH3CH2CH2CH3 (Butane) -> CH3CH2CH2CH2 (Butyl)

Propane:

CH3CH2CH3 (Propane) ->CH3CH2CH2 (Propyl)

Self-evaluation problem 11.6:

  • From A to E are the structural formulae of certain chemical compounds.
identify branched chain cyclic and straight chain organic compounds

Give the letters which represents:

  1. Branched-chain compounds
  2. Cyclic compounds
  3. 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 a cyclic compound as we can see that all the carbon atoms are arranged in a 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.

  1. CH3-CH2-O-CH2-CH3
  2. CH3-CH2-CH2-OH
  3. C6H5OH
  4. C2H5OH

Answer:

  1. 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-).
  2. 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.
  3. 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:

Determine whether each of the following substances is an aldehyde, ketone, or carboxylic acid.

identify aldehyde ketone and carboxylic acid

Answer:

  1. 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.
  2. 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.
  3. 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

Make a distinction between saturated and unsaturated substances using potassium permanganate and iodine bromine.

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

Recognize the functional groups of carboxylic acids, phenols, amines, aldehydes, and ketones in a laboratory.

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.

———————————

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