Tag: what

Is sublimation a chemical change or a physical change ?

In a physical change the nature of substance remains same . The properties remains same. But in case of chemical change the new kind of substance is formed, with different nature. “Sublimation is a process in which a substance changes its state from solid into vapour directly”. So the point to note here is that

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Stobbe reaction and its Mechanism

It is a type of condensation reaction that involves the condensation of an aldehyde or ketone with succinic ester in the presence of sodium ethoxide or Potassium ethoxide to yield unsaturated ester acid . The complete reaction is as below. The mechanism involves 3 steps , and firstly the succinate is treated with base to

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How many lone pairs of electrons are on the S atom in sulphur tetra floride (SF4) ?

In case of SF4 there are 6 electrons in the outermost shell of Sulphur, out of these 6 electrons, 4 are utilized in bonding with fluorine and thus two unshared electrons are there. Which leads to the lone pair as shown below. Contribute to make this site more informative.

What is hydrogen bond? How does an intermolecular hydrogen bond differ from intramolecular hydrogen bond ?

Actually the hydrogen bond is simply a type of attraction which is caused by the the electronegativity difference between hydrogen and highly electronegative element like oxygen carbon nitrogen and fluorine. Intermolecular hydrogen bonding takes place between two molecules having hydrogen and electronegative element. Hydrogen is attracted by the electronegative element of another molecule for example

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What are Colligative properties ?

Actually the word co-ligative itself reveals that (“co” means each other and “ligative” means related) These are the properties which are related to each other. The colligative properties are those properties that depend on the number of solute particles in a solution or a mixture. “These properties don’t depend upon the nature of particles “.

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Why is carbon important for forming complicated molecules? Or why carbon makes a large number of molecules ?

The answer to this question is very simple . There are two major reasons behind it. 1. Catenation :- It is the property by which the carbon can make long chains, branched chains and ring or cylic structural by joining with its own atoms. Due to this it can make a variety of molecules. 2.

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Why H3PO3 is a diprotic acid? Give reason with structure .

Meaning of diprotic acid is that , it can loose two hydronium ions (H+) . For finding how many H+ ions it can give , we have to see its structure. Here it have only two hydroxyl groups that is -OH groups, and the hydrogen atoms joined to these only are ionisable. So only these

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Preparation of chlorobenzene – Sandmeyer’s reaction

Chlorobenzene and bromobenzene can be prepared by treating bezenediazonium chloride with cuprous chloride or cuprous bromide. This reaction is also called Sandmeyer’s reaction. The reaction is named after the Swiss Chemist Traugott Sandmeyer. In this reaction the diazonium group losses the molecule of dinitrogen and it yields chlorobenzene.

Why sigma bond is stronger than pi bond?

Actually the sigma bond involves head to head overlapping of orbitals, due to which the overlapping takes place on a larger extent. That makes the bond more stronger as compared to pie bond. In pie bond there is a sidewise overlapping of orbitals which leads to lesser extent of overlapping and thus the bond formed

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What are the factors that affect Vapour Pressure?

1.Temperature :- With increase in temperature the rate of vaporization also increase thus it creates more pressure. Moreover with increase in temperature the kinetic energy of the vapours also increase. 2. Nature of liquid:- The liquids with lower inter-particulate attractions have high vapour pressure as the formation of vapours is easy . Like acetone is

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Semiconductor and its types.

The substances whose conductivity lies between 10-⁶ to 10⁴ ohm-¹ . The range lies between conductors and insulators. Types 1. n-type :- These type of semiconductors have excess electrons present in the lattice that are responsible for the conduction. These are formed when the group 14 elements like Silicon are doped with group 15 elements

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Explanation of Paramagnetism, ferromagnetism, ferrimagnetism and antiferromagnetism .

1. Paramagnetism :- This is the phenomenon by which substances are weekly attracted by the magnetic field. It arises because the substances are magnetized in the same direction of the applied magnetic field. This property is shown by the atom, ions or the molecules that contain unpaired electrons. 2. Ferromagnetism:- This is the phenomenon by

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Explanation of Schottky defect, Frankel defect, Interstitial defect and F-centres.

1. Schottky defect:- In this kind of defect equal number of cations and anions are missing from the crystal lattice. Due to this the vacant sites or the holes are present in the lattice. This kind of defect is present in the ionic compounds with high coordination number and equal size of ions. Density of

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Some important terms

1. Co-ordination number Number of spheres touching one Sphere in a close packed structure is called co-ordination number of a lattice 2. Unit cell The smallest repeating pattern in a crystal lattice is called a unit cell. Characteristics of unit cell Are unit cell has a characteristic dimensions along the three edges a,b,c and interfacial

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