Carbon and Carbon Compounds – Maharashtra Board Class 8 Solutions for General Science (English Medium)
The elements found in more than one form in nature and having the same chemical properties but different physical properties are called allotropes of an element.
Allotropes of carbon are of two types – crystalline and amorphous.
The crystalline allotropes of carbon are diamond, graphite and fullerene.
The amorphous allotropes of carbon are coke and coal.
Production of carbon dioxide gas in the laboratory:
- Place some pieces of calcium carbonate in a flask.
- Pour some dilute hydrochloric acid through a funnel into the flask.
- Ensure that the lower end of the funnel tube dips into the hydrochloric acid.
- A chemical reaction takes place between calcium carbonate and hydrochloric acid.
- Carbon dioxide gas released gets collected in the jar by the upward displacement of air.
Graphite is smooth and slippery because of the specific arrangement of its carbon atoms. Hence, graphite is used as a lubricant.
Charcoal is produced by burning substances of plant origin such as wood in an insufficient supply of oxygen.
Diamond is used to cut metals because it is extremely hard.
Carbon dioxide is used for putting out fires because it neither burns nor supports burning.
- Graphite is a good conductor of heat and electricity.
- Fullerene is an allotrope of carbon.
- Carbon dioxide turns limewater milky.
- Charcoal is an amorphous form of carbon.
- Diamond is a bad conductor of electricity.
- A biogas plant produces methane gas.
|a. Fullerene||4. C60|
|b. Graphite||3. Hexagonal arrangement of atoms|
|c. Diamond||2. Cutting metals|
|d. Washing soda||1. Na2CO3|
a. Uses of carbon:
a. Carbon is the main constituent of plants and animals.
b. Diamond, an allotrope of carbon, is used in making ornaments of jewellery.
b. Uses of carbon dioxide:
a. It is used to produce aerated cold beverages.
b. It is used in fire extinguishers.
c. Uses of methane:
a. It is used as a fuel.
b. It is used to produce acetylene.
|S.No.||Crystalline form of carbon||Amorphous form of carbon|
|a.||The atoms of the elements in the crystalline form have a specific arrangement.||The atoms of the elements in the amorphous form have an irregular arrangement.|
|b.||Carbon in the crystalline form is an extremely hard material.||Carbon in non-crystalline form is brittle.|
|c.||The examples of crystalline forms of carbon are diamond and graphite.||The examples of amorphous forms of carbon are coke and coal.|
|a.||It is extremely hard.||It is soft, smooth and slippery.|
|b.||It is a bad conductor of heat and electricity.||It is a good conductor of heat and electricity.|
|c.||In a diamond crystal, each carbon atom is linked to four other carbon atoms at a specific distance.||Six carbon atoms form a hexagon and are at a specific distance from each other. Within each layer, every carbon atom has three other carbon atoms around it at equal distances.|
|d.||It is used as an ornament of jewellery, to cut glass and in drilling machines.||It is used as a lubricant.|