(c)
Name the gas evolved in each of the following cases:
(i) Copper carbonate is heated strongly.
Answers
Answer:
co2 is the gas evolved when copper carbonate is heated ( ig)
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iii
c. Write the
They have sharp and characteristic melting points.
iv
When cut with a sharp-edged tool, they cut into two pieces with irregular shapes.
iv
When cut with a sharp-edged tool, they split into two pieces with plain and smooth newly-generated surfaces as shown in the figure.
If the bulb glows on attaching the clips to both the ends of the graphite in the pencil, it means that graphite conducts electricity. If the bulb does not glow it means that graphite does not conduct electricity.
c. Carbon has the following properties:
Physical properties:
Carbon is a soft, dull gray or black non-metal.
It exists in two forms i.e. crystalline and non crystalline forms. This property is termed as allotropy.
Chemical properties:
The chemical properties of carbon ca be explained on the basis of reactions which carbon and its compound show.
1. Combustion reaction:
Carbon, in all its allotropic forms, burns in oxygen to give carbon dioxide along with the release of heat and light. This reaction is termed as combustion reaction.
The chemical equation to represent the burning of carbon is as follows:
2. Oxidation reaction: Pure carbon is oxidized to give carbon dioxide when burnt in air. Similarly, hydrocarbons can be easily oxidized on burning. Substances that have the ability to oxidize other substances are known as oxidizing agents. Alkaline potassium permanganate and potassium dichromate are examples of oxidizing agents. For example, the oxidation of ethanol in the presence of potassium permanganate leads to the formation of ethanoic acid.
3. Addition reaction: In an addition reaction, a substance is added to a hydrocarbon. A single product is obtained in this reaction. In unsaturated hydrocarbons, double or triple bonds are present. Atoms of different elements like hydrogen, chlorine, bromine etc. are added to these compounds across the double or triple bonds using different reagents and catalysts.
4. Substitution reaction: It is a type of reaction in which an atom or a group of atoms replaces another atom present in a molecule undergoing the reaction. For example, chlorine replaces hydrogen from methane in the presence of sunlight.
d. Carbon exists in two different forms i.e. allotropic and amorphous forms.
i. Crystalline forms:
Diamond: In diamond, each atom of carbon of the given crystal unit is surrounded by four other carbon atoms, which are joined by covalent bonds, such that they form a regular tetrahedron. The diamond crystal is a compact structure in which atoms of a single unit lie in different planes. Thus, the atoms cannot slip because of their different positions in different planes and hence, diamond is the hardest naturally occurring substance.