5. Give reasons for the following: (i) Diamond has a high melting point. (ii) Graphite is a good conductor of electricity. (iii) Acetylene burns with a sooty flame.?

Question

Answer

(1)Each carbon atom is covalently bonded to four other carbon atoms in diamond. A lot of energy is needed to separate the atoms. This is because covalent bonds are strong. This is the reason why diamond has a high melting point.
(2)In a graphite molecule, one valence electron of each carbon atom remains free, Thus making graphite a good conductor of electricity. Whereas in diamond, they have no free mobile electron. Hence there won't be flow of electrons That is the reason behind diamond are bad conductor electricity.
(3)Ethyne (acetylene) burn with a sooty flame because ethyne is an unsaturated hydrocarbon and the percentage of carbon in these hydrocarbons is comparatively higher which does not get oxidised completely in oxygen of air.

Answer

Diamond has a high melting point because the forces of attraction between the molecules of diamond is very large and a large amount of heat is in the form of energy of heat is required to break that bonds between the Diamond molecules.

Graphite is a good conductor of electricity because it contains free molecules which contains electrons which helps in conduction of electricity.

Acetylene burns with a sooty flame because it contains a high percentage of carbon in it which when react with oxygen gets oxidized carbon dioxide and give soot.

Answer

Reasons for the following:

(i) Diamond has a high melting point:

Diamond is a form of carbon in which the carbon atoms are arranged in a rigid three-dimensional lattice structure. This structure consists of strong covalent bonds between each carbon atom, resulting in a highly compact and stable arrangement. The high melting point of diamond can be attributed to the following reasons:

1. Strong covalent bonds: The carbon atoms in diamond are bonded to four neighboring carbon atoms through strong covalent bonds. These bonds are very difficult to break, requiring a significant amount of energy. As a result, diamond has a high melting point.

2. Rigid and compact structure: The three-dimensional lattice structure of diamond is highly rigid and densely packed. This arrangement minimizes empty spaces between the atoms, making it difficult for them to move and vibrate. The strong bonds and compact structure contribute to the high melting point of diamond.

3. Lack of free electrons: Unlike metals, diamond does not have any free electrons that can move within the lattice and conduct heat. This lack of mobile charge carriers restricts the transfer of heat energy, further increasing the melting point of diamond.

(ii) Graphite is a good conductor of electricity:

Graphite is another form of carbon, but its structure is different from that of diamond. In graphite, carbon atoms are arranged in layers of hexagonal rings, with each carbon atom bonded to three neighboring carbon atoms. The reasons why graphite is a good conductor of electricity are as follows:

1. Delocalized electrons: In the hexagonal layers of graphite, each carbon atom forms three strong covalent bonds with its neighboring atoms, leaving one electron uninvolved in bonding. These uninvolved electrons are delocalized and can move freely within the layers. This delocalization of electrons allows graphite to conduct electricity.

2. Weak interlayer forces: Although the carbon atoms within each layer of graphite are strongly bonded, the forces of attraction between the layers are relatively weak. These weak interlayer forces allow the layers to slide over each other, making graphite soft and slippery. At the same time, they also enable the movement of electrons between the layers, facilitating electrical conductivity.

3. Presence of free electrons: The delocalized electrons in graphite act as charge carriers and can easily move through the layers, carrying electrical current. This presence of free electrons makes graphite a good conductor of electricity.

(iii) Acetylene burns with a sooty flame:

Acetylene (C2H2) is a hydrocarbon gas that is commonly used as a fuel for welding and cutting metals. When acetylene burns, it produces a flame that is characterized by its sooty nature. The reasons for the sooty flame produced by acetylene are as follows:

1. Insufficient oxygen supply: The sooty flame of acetylene is a result of incomplete combustion. When acetylene burns, it requires an adequate supply of oxygen to completely react with the carbon and hydrogen atoms in the molecule. However, in certain conditions, such as when there is limited oxygen available, the combustion process is incomplete.

2. Carbon-rich fuel: Ac

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