Class 10 Hydrocarbon Exercise 18.1 Solutions | Science and Technology Curriculum Development Centre

Differences between saturated and unsaturated hydrocarbon are given below:

Differences between alkane and alkene are as follows:

Differences between monohydric alcohol and dihydric alcohol are:

Saturated hydrocarbons are those hydrocarbons in which carbon atoms are bonded by single covalent bond.

Hence, Ethane(C₂H₆) is known as a saturated hydrocarbon because its atoms carbon atoms are bonded together by a single covalent bond only.

The alcohol having three hydroxyl groups(-OH) in one compound is called trihydric alcohol.

Hence, Glycerol [C₃H₅(OH)₃] is called a trihydric alcohol because it has three hydroxyl group(-OH) after the removal of 3 hydrogen atoms from propane. It is the simplest trihydric alcohol.

Hydrocarbons are compounds formed by the covalent bonding between hydrogen and carbon atoms. Generally, they are organic compounds.

Any four examples of hydrocarbons are Methane, Ethane, Propane, and Alcohol.

Saturated hydrocarbons are those hydrocarbons in which carbon atoms are bonded together by a single covalent bond only. Alkanes are known as saturated hydrocarbons.

Some of the examples of saturated hydrocarbons are: Methane, Ethane, Pentane, Heptane etc.

Methane:

 Methane is a saturated hydrocarbon. It is the simplest and the first member of the alkane series. It is also known as marsh gas because it is found in swamps or marshy land where it is produced by bacterial decomposition of complex vegetables and animal matters.                        

Molecular formula of methane: CH₄ 

Uses of methane are:

1. It is used as a gaseous fuel in industries and household works.
2. It is used for making printing ink.

Alcohol is defined as an organic compound containing hydroxyl group(-OH) attached to a saturated carbon atom or hydrocarbon radical.

On the basis of number of hydroxyl group(-OH) in the molecule of alcohol, it is classified into three types as given below:

1. Monohydric alcohol: The alcohol having only one (-OH) group in the molecule is called monohydric alcohol. Its general formula is ( \(\rm C_{n}H_{2n+1}OH\) ). 

Example; methyl alcohol( \(\rm CH_{3}OH\) ). Its structural formula is:

2.Dihydric alcohol: The alcohol having two hydroxyl groups(-OH) in one compound is called dihydric alcohol. Its general formula is ( \(\rm C_{n}H_{2n}(OH)_{2}\) ). 

Example; ethylene glycol ( \(\rm C_{2}H_{4}(OH)_{2}\). Its structural formula is:

3. Trihydric alcohol: The alcohol having three hydroxyl groups (-OH) in one compound is called trihydric alcohol. Its general formula is ( \(\rm C_{n}H_{2n-1}(OH)_{3}\) ). 

Example; glycerol ( \(\rm C_{3}H_{5}(OH)_{3}\). Its structural formula is:

1. Ethylene: Molecular formula: ( \(\rm C_{2}H_{4}\) )

                  Condensed formula: ( \(\rm C_{2}H_{2}= C_{2}H_{2}\) )

                   Structural formula:

2. Propene: Molecular formula: ( \(\rm C_{3}H_{6}\) )

                    Condensed formula: ( \(\rm CH_{2}= CH - CH{3}\) )

                    Structural formula:

3. Acetylene: Molecular formula: ( \(\rm C_{2}H_{2}\) )

                       Condensed formula: HC≡CH

                       Structural formula:

4. Ethyl alcohol: Molecular formula:  ( \(\rm C_{2}H_{5}OH\) )

                            Condensed formula:  ( \(\rm CH_{3}-CH{2}-OH\) )

                            Structural formula: 

5. Glycerol :  Molecular formula:  ( \(\rm C_{3}H_{5} (OH)_{3}\) )

                      Condensed formula:  ( \(\rm CH_{2}OH-CHOH-CH_{2}OH\) )

                      Structural formula: 

1. to make formaldehyde. Ans: Methyl alcohol
2. used in thermometer. Ans: Ethyl alcohol
3. used as an antiseptic. Ans: Ethyl alcohol 
4. to prepare alcoholic beverages. Ans: Ethyl alcohol

Ethylene (IUPAC name: ethene) is the simplest alkene with the chemical formula ( \(\rm C_{2}H_{4}\) ).The structural formula of ethylene is:

• The bonds between hydrogen and carbon are strong because they share their electrons directly.
• The double bond between carbon atoms is a bit weaker because the atoms are crowded, it has a mix of strong and weak bonds, and the electrons in one part of the bond are spread out instead of being tightly held.

Uses of Methane:

1. It is used as a gaseous fuel in industries and household works.
2. It is used for making printing ink.
3. It is used for making carbon black needed for paints and rubber industries.

Major uses of ethane are:

1. Ethane is used as a gaseous fuel along with methane.
2. It is used for preparing other organic compounds like ethyl alcohol, diethyl ether, etc.
3. It is used for making shoe polish.

Propane is a type of alkane with molecular formula ( \(\rm C_{3}H_{8}\)).

Major uses of propane are:

1. Propane is used as a fuel in lighters and also as a refrigerant.
2. It is used to make other type of compounds like glycerol.
3. It is used in petroleum industries for cooling purpose.

Saturated hydrocarbons are those hydrocarbons in which carbon atoms are bonded together by a single covalent bond only.

The compounds in which carbon atoms are linked together by multiple bonds(either double or triple covalent bons) are known as unsaturated hydrocarbons.

An alkane is a type of hydrocarbon in which the carbon atoms are connected by single bonds only. The general formula for alkanes is ​C_nH_2n+2, where n represents the number of carbon atoms.

An alkene is a type of unsaturated hydrocarbon in which the one pair of carbon atoms are bonded by double covalent bonds. The general formula for alkanes is ​C_nH_2n, where n represents the number of carbon atoms.

A functional group is defined as an atom or a group of atoms that define the chemical properties of an organic compound when added to it.

Some examples of functional groups are: Alcohol (-OH), Aldehyde (-CHO), Ether (-O-), etc.

In organic compounds, there exists a series or a group of compounds having the same functional group and similar chemical properties in which each succeeding compound differs from the preceding by -CH2 group or 14 molecular weights. Such a series is known as the homologous series. 

In other words, homologous series is defined as a series of organic compounds in which all the organic compounds can be represented by the same general formula and each successive homologue differs from the preceding by a -CH2 group or 16 molecular weight.

The molecular formulae of the given compounds are:

• Glycerol: $\rm (C_{3}H_{5})(OH)_{3}$
• Methane: $\rm CH_{4}$
• Ethanol: $\rm C_{2} H_{5} OH$
• Butane: $\rm C_{4}H_{10}$
• Propane: $\rm C_{3}H_{8}$
• Acetylene: $\rm C_{2}H_{2}$
• Ethene: $\rm C_{2}H_{4}$
• Ethane: $\rm C_{2}H_{6}$
• Propyne: $\rm C_{3}H_{4}$
• Methyl Alcohol: $\rm CH_{2} OH$

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Glycerol is formed by the replacement of three hydrogen atoms with three hydroxyl groups    (-OH) making it the simplest trihydric alcohol.                                                                                     

Its IUPAC name is Propane- 1,2,3-triol. Its structural formula is:

Uses of Glycerol:

1. Glycerol is used as a sweetening agent in confectionery, beverages and medicines.
2. It is used as a lubricant in watches.
3. It is used in the preparation of printing inks and stamp pad inks.

Glycerol is a alcohol used to manufacture good quality soaps and cosmetics. Hence, Glycerol can be used by Rama to solve her problems.

Additionally, when water is mixed with glycerol, it forms glycerin. Glycerin draws moisture from the environment into the skin, helping to hydrate and improve its appearance. This can solve the problem with dry skin on her hands, feet, and face.

The IUPAC name of glycerol is propane-1,2,3-triol.

Its structural formula is: