Carbon And Carbon Compounds

In nature, some elements are found in more than one form. Even though the chemical properties are the same, they have different physical properties. These forms are called allotropes of an element and this property of an element is called allotropy.

Carbon occurs in crystalline allotropes and non-crystalline(amorphous) allotropes.

Carbon dioxide gas produced in the laboratory by the following steps:

Step 1: Some pieces of calcium carbonate-CaCO₃ (limestone) in a flask is placed.

Step 2: The apparatus is set up as shown in the diagram below:

Step 3: Through a funnel that reaches the base of the flask, dilute hydrochloric acid is poured.

Step 4: The lower end of the funnel tube is dipped into the HCl.

Step 5: A chemical reaction takes place between calcium carbonate and HCl.

Step 6: The carbon dioxide that is evolved will collect in the gas jar by displacement reaction.

Overall reaction: CaCO₃ + 2HCl → CaCL₂ + H₂O and 1/2O₂

Graphite is used as a lubricant due to the following reasons:

i. A graphite crystal is hexagonal.

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

iii. The layers are loosely bounded with each other.

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

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

Weak bond between layers

Charcoal is made by burning substances of plants origin (like wood) in an insufficient supply of oxygen.

Wood + oxygen (insufficient supply) → Charcoal

Diamond is used to cut metals due to the following reasons:

i. Brilliant, pure diamond is an extremely hard substance on the earth.

ii. It is really very harder than metals and rocks present in the earth.

iii. Hence, it used to cut metals.

Fact: One of the heritage monument of India, Taj Mahal, the designs on marble were done by attaching a diamond to the end of a screwdriver. Now we can imagine the power of a diamond.

Carbon dioxide is used for putting out fires due to the following reasons:

i. CO₂ is filled under pressure in the fire extinguisher.

ii. When we decrease that pressure, it becomes gaseous and comes out forcefully.

iii. The carbon dioxide produces and gushes out of the cylinder and as a result, it displaces the oxygen (a main cause of fire to burn)

iv. By removing oxygen, we can put out a fire.

v. The reaction taking place:

Graphite is a good conductor of heat and electricity.

Explanation:

i. In graphite, carbon atoms are arranged in different layers.

ii. In each layer, every carbon atom is linked to three neighboring carbon atoms.

iii. Thus, the fourth electron of each carbon atom is free to move continuously within the entire layer.

iv. Because of the presence of these free electrons in different layers, graphite becomes a good conductor of heat and electricity.

Fullerene is an allotrope of carbon.

Explanation:

i. Fullerene is a crystalline allotrope of carbon.

ii. It is a recently discovered allotrope of carbon.

iii. In crystalline allotrope, there is a proper arrangement of atoms. Fullerene has specific arrangement of atoms.

iv. It exists in the form of buckyball.

Structure of fullerene

Carbon dioxide turns limewater milky.

Explanation:

When limewater (CaOH) �₂ is passed through CO₂, the following reaction takes place:

i. In this reaction, when limewater comes in contact with the gas released in the form of an effervescence, it turns milky. This is chemical test for carbon dioxide gas.

ii. When limewater turns milky, it is confirmed that the effervescence is of carbon dioxide.

Charcoal is an amorphous form of carbon.

Explanation:

In amorphous form, there is indefinite and irregular arrangement of atoms. Charcoal shows all the properties of an amorphous form.

Diamond is a bad conductor of electricity.

Explanation:

i. Diamond exists in tetragonal three-dimensional structure.

ii. Structure of diamond:

Diamond has no free electrons moving inside, thus it is a bad conductor of electricity.

A biogas plant produces methane gas.

Explanation:

i. We obtain methane in a biogas plant.

ii. Methane is produces in biogas plant anaerobically (in the absence of air).

iii. It is produced by the waste from plants and animals.

Two uses of carbon:

i. Carbon is used as a fuel.

ii. Carbon as diamond is used to cut the metals.

iii. Carbon as graphite is used as lubricant.

iv. Carbon as carbon dioxide is used to produce dry ice.

(any two)

Two uses of carbon dioxide:

i. Carbon dioxide is used to put out fires.

ii. Carbon dioxide is used to make washing soda (Na₂CO₃)

iii. Plants make their own food using carbon dioxide.

iv. Carbon dioxide is used to produce aerated cold drinks.

(any two)

Two uses of methane:

i. Methane (CH₄) is mainly used as a fuel to make heat and light.

ii. Methane is used in homes for cooking and heating.

iii. Methane is used to produce other carbon compounds. (like ethane)

iv. Methane is also used in the production of electricity.

(any two)

Difference between crystalline and non-crystalline forms of carbon:

Difference between diamond and graphite:

The different kinds of coal present are:

i. Anthracite – It contains 80% of carbon.

ii. Bituminous coal – It contains 60% of carbon.

iii. Lignite – It contains 22% of carbon.

iv. Peat – It contains 11% of carbon.

Uses of different types of coals are:

i. Anthracite – It is used in the metallurgical process and to slow combustion stoves at home.

ii. Bituminous coal – It is widely used for in the production of gas and coke. It is also used in steam rising.

iii. Lignite - It is used in the production of electricity.

iv. Peat – It is used generally as a fertilizer used in the farms.