Q61 of 66 Page 156

What is meant by hybridisation? Compound CH2 = C = CH2 contains sp or sp2 hybridised carbon atoms. Will it be a planar molecule?

Hybridization is a term coined by a scientist Pauling in 1931.

It is an imaginary concept which shows the intermixing of the orbitals to form a new one, which is of approachable in energy, to make a bond.


It will be more easy to understand with an example, so let say we have to form a bond between the C atom and a H atom, we know that the bond can be formed by the overlapping of the orbitals, so for the proper overlapping of the orbitals, the energy of the orbital must be comparable, but in this case it is not, hence, the orbitals of C, i.e s and p orbitals of C get mixed and form a new sp3 orbital, which can easily overlap with the s orbital od the H-atom. Hence, the bond can be formed easily now after hybridisation.


Now, checking the hybridisation of the carbon atoms in the molecule CH2 = C = CH2.


The molecule CH2 = C = CH2 contains both sp as well as the sp2 hybridised carbon atoms.


The two terminal Carbon atoms are forming three sigma bonds so, the hybridisation will be sp2 , whereas the central carbon atom is forming only two sigma bonds so, the hybridisation will be sp.


As we know that the hybridisation of any atoms is predicted by considering the number of the sigma bond formed by that particular atom and the loan pair of electrons present at the atom.


The molecule will be planar as the sp2 hybridisation leads to trigonal planar shape and sp leads to formation of linear geometry.


Hence, the molecule CH2 = C = CH2 is overall planar molecule.


More from this chapter

All 66 →
59

In the following questions a statement of Assertion (A) followed by a statement of

Reason (R) is given. Choose the correct option out of the choices given below each question.


Assertion (A): Sulphur present in an organic compound can be estimated quantitatively by Carius method.


Reason (R): Sulphur is separated easily from other atoms in the molecule and gets precipitated as light yellow solid.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct.


 60

In the following questions a statement of Assertion (A) followed by a statement of

Reason (R) is given. Choose the correct option out of the choices given below each question.


Assertion (A): Components of a mixture of red and blue inks can be separated by distributing the components between stationary and mobile phases in paper chromatography.


Reason (R): The coloured components of inks migrate at different rates because paper selectively retains different components according to the difference in their partition between the two phases.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv)A is not correct but R is correct.


 62

Benzoic acid is an organic compound. Its crude sample can be purified by crystallisation from hot water. What characteristic differences in the properties of benzoic acid and the impurity make this process of purification suitable?

 63

Two liquids (A) and (B) can be separated by the method of fractional distillation. The boiling point of liquid (A) is less than boiling point of liquid (B). Which of the liquids do you expect to come out first in the distillate? Explain.