Carbon And Its Compounds

The simplest hydrocarbon is CH₄ (methane)

Note: Hydrocarbons are the compounds containing only carbon and hydrogen in their molecules.

Alkanes

i. Hydrocarbons containing only one single bond between carbon atoms are called alkanes.

ii. The general formula is C-C.

Alkenes

iii. Hydrocarbons containing at least one double bond between carbon atoms are called alkenes.

iv. The general formula is C=C.

Alkynes

v. Hydrocarbons containing at least one triple bond between carbon atoms are called alkynes.

vi. The general formula is CΞC.

Acetic acid (ethanoic acid) is widely used as a preservative in pickles.

When ethanol is burnt in the presence of air, it forms CO₂ gas and water.

CH₃CH₂OH → 2CO₂ + H₂O

i. Ethanal

Explanation: For an aldehyde, we have to add the suffix “—al”. Thus, IUPAC name of an aldehyde derived from ethane will be ethanal.

ii. Butanone

Explanation: For a ketone, we have to add the suffix “—one”. Thus, IUPAC name of a ketone derived from butane will be butanone.

iii. Chlropropane

Explanation: For a chloride, we have to add the prefix “chloro-”. Thus, IUPAC name of a chloride derived from propane will be chlropropane.

iv. Pentanol

Explanation: For an alcohol, we have to add the suffix “—ol”. Thus, IUPAC name of a ketone derived from butane will be butanone.

A mixture of ethyne and air is not used for welding because when ethyne is burnt in air, it gives sooty flame which is not suitable for welding.

In addition reaction, the unsaturated fatty acids(oil) are converted to saturated fatty acids (ghee).

The simplest ketone is propanone.

The structure of propanone is:

Self-linking property of carbon is called catenation. If any element forms bond between its own atoms to give big molecules. This property is called catenation.

Note: This ability of carbon to form a bond in so many ways made it as a versatile element in nature.

When ethanol is heated in the presence of concentrated H₂SO₄ in excess, the compound formed is ethene.

Note: The above reaction is a dehydration reaction. H₂SO₄ is a dehydrating agent and removes water (H₂O).

Esterification reaction—The reaction between carboxylic acid and an alcohol in the presence of con. H₂SO₄ to form ester is called esterification.

When ethanol is oxidized by either anhydride or alkaline potassium permanganate, the compounds formed are ethanol and ethanoic acid.

Preparation of ethanol from ethane

Step 1: Ethane reacts with chlorine in the presence of sunlight to form chloroethane.

Step 2: Now, chloroethane reacts with NaOH to form ethanol by the replacement of Cl atom by OH.

CH₃CH₂Cl + NaOH → CH₃CH₂OH

The IUPAC name of the given compound (CH₃OHCH₂CH₃) is propane-2-ol. The IUPAC name of the next homologous of CH₃OHCH₂CH₃ is but-2-ol.

Homologous series: The series of carbon compounds in which two successive compounds differ by –CH₂ unit is called homologue series.

Example:

● CH₄, C₂H₆, C₃H₈…..

● CH₃OH, C₂H₅OH, C₃H₇OH….

Characteristics

i. They have one general formula.

ii. Each compounds in the series differs by –CH₂ group.

iii. They have similar chemical properties due to the same functional group.

i. Aldehyde

ii. Ketone

Carbon forms the compound mainly by covalent bonding due to the following reasons below:

i. The electronic configuration of carbon is 2, 4.

ii. If four electrons are added to the second orbit of carbon, its octet becomes complete and its electronic configuration becomes stable like that of the nearest inert gas neon (2, 8).

iii. Therefore, the valency of carbon is 4. However, this occurs by sharing of electron rather than a give and take of electrons.

iv. That’s why a carbon atom can form four covalent bonds with other carbon atoms or atoms of different elements.

Allotropy

i. Some elements occur in nature in more than one form.

ii. The chemical properties of these different forms are the same but their physical properties are different. This property of elements is called allotropy.

iii. Like carbon, sulphur and phosphorus also exhibit allotropy.

iv. The different forms of the element are called allotropes.

The allotropes of carbon are classified into two types

i. Amorphous forms – coal, coke, wood, charcoal, animal charcoal etc.

ii. Crystalline forms – diamond, graphite, and fullerene

Ethanol reacts with metallic sodium to form sodium ethoxide and hydrogen is liberated. The chemical equation is given below:

By oxidation of ethanol

When ethanol is oxidized by either anhydride or alkaline potassium permanganate, the compound formed is ethanol. On further oxidation, it forms ethanoic acid.

The chemical reaction is given below:

Cleansing action of soap

i. Soap has one polar end and one non-polar end.

ii. The polar end is hydrophilic in nature and attracted towards water whereas the non-polar end is hydrophobic in nature and attracted towards the oil or grease

iii. When soap is dissolved in water, its hydrophobic ends attach to the dirt.

iv. The hydrophobic ends try to pull out the dirt.

v. The molecules of soap surround the dirt particles at the center of the cluster and form a spherical structure called micelle.

vi. The dust particles remain trapped in micelles which are easily rinsed away with water.

vii. That’s how soap clean the clothes.

Structure of graphite

i. In graphite, every carbon atom is bonded to three other carbon atoms by covalent bonds.

ii. A graphite crystal is hexagonal.

iii. The regular arrangement of atoms in graphite is in hexagonal layers.

Property – A good lubricant

iv. The layers are loosely bounded with each other.

v. As there is a weak force of attraction present between them, hence the layers slide with each other.

vi. This makes the graphite slippery and thus it used as a lubricant.

Carboxylic acid is present in vinegar.

When a small piece of sodium is dropped into ethanol, it forms sodium ethoxide (C₂H₅ONa). The reaction is given below:

C₃H₆ is most likely to show addition reaction.

Explanation:

The additionreaction is shown by the unsaturated compounds which contain double bonds or triple bonds like alkenes and alkynes.

C₃H₈ – is a saturated hydrocarbon as it does not contain double bonds or triple bonds.

On the other hand, C₃H₆ – is an unsaturated hydrocarbon as it contains a double bond. Thus, C₃H₆ undergoes addition reaction.

To find the hardness of water

Step 1: Take some distilled water in a test tube and hand pump water in another test tube.

Step 2: Add some drops of soap solution to both the tubes.

Step 3: Shake both the tubes together. Observe the foam formed.

The test tube having distilled water shows more foam whereas the test tube having hand pump water forms a white precipitate due to the presence of calcium and magnesium ions. This indicates that it is a hard water.

a. ‘X’ is ethanol (CH₃CH₂OH) and ‘Y’ is ethanoic acid (CH₃COOH)

b. When the ethanol(alcohol) is made to react with ethanoic acid (carboxylic acid), the compound formed is ester and this process is called esterification.

i. Calcium carbide is one of the main artificial ripening agents of fruits. It speeds up the ripening process.

ii. When calcium carbide comes in contact with air, it produces ethylene.

iii. Ethylene effects of ripening are almost similar as natural ripening agents.

iv. That why it is most preferred.

Role of esters in everyday life

1. Esters have sweet odouring substances.

2. Majority of fruits owe their odour to a particular ester present in them.

3. Esters are used for making fragrances, perfumes and flavouring agents.

4. Esters are used in the saponification to prepare soaps.

i. Consumption of small quantities of dilute ethanol shows its effect even though is condemned still it has remained socially widespread practice.

ii. Consumption of alcohol harms health in a number of ways.

iii. It adversely affects the physiological processes.

iv. It damages the central nervous system.

v. Consumption of even a small quantity of pure ethanol (called absolute alcohol) can be lethal.

a. The organic compound is CH₃COOH.

b. Ethanoic acid (CH₃COOH) reacts with sodium carbonate (Na₂CO₃) to form sodium acetate and liberate CO₂

CH₃COOH + Na₂CO₃→CH₃COONa + CO₂

c. The gas evolved is CO₂.

d. The CO₂ gas of the effervescence passes through the gas delivery tube and reacts with the lime water in the small test tube. ‘Lime water turning milky’ is the test of carbon dioxide gas.

e. Two important uses of ethanoic acid are:

i. It is used as a preservative for pickles.

ii. It used in making vinegar.

a. The resultant compound formed is ester.

b.

c. The term given to such reaction is esterification reaction.

d. The compound formed is ester which has sweet-smelling and is used to make perfumes and fragrances.