Predict the structure of methane based on hybridization.
Ans: Methane is a tetrahedral covalent molecule having bond angle 10928′. The mode of hybridization in C-atom in methane is .
The tetrahedral structure of methane on the basis of hybridization can be explained as follows:
The electronic configuration of C and H are
Mode of hybridisation in Methane
One of the 2-S electrons is promoted to vacant 2 P- orbital (namely ). All of the four orbitals (one S and three 2 P orbitals) undergo hybridisation so as to form four hybrid orbitals. All these four hybrid orbitals are directed towards the four corners of a regular tetrahedron making an angle of 10928′ to each other.
Now, all the four hybrid orbitals of C-atom overlap with four 1 S- orbitals of four H- atoms by end to end method to form four covalent bonds of identical energy value with tetrahedral geometry.
Fig: Formation of molecule
Therefore, Methane has got tetrahedral structure with four covalent bonds having each H-C-H bond angle = 10928′.
What is H- bonding?
Ans: Hydrogen, which is bonded covalently with strongly electronegative element, can again form an extra weak physical bond with electronegative element; such weak bond is known as hydrogen bond. i.e. The electrostatic force that binds H-atom of one molecule with electronegative atom of the other molecule of the same substance or of the different compound or within the same molecule is known as H- bonding.
Hence, hydrogen – bond is electrostatic in origin. It – is represented by (……) dotted line.
It is of two types
i. Inter-molecular H-bonding [Association]
ii. Intra-molecular H-bonding [Chelation]
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3.Define decinormal solution.
Ans: A solution containing 1/10th gram-equivalent of the solute is know as decinormal (N/10) solution.
Eg. If 4 gm NaOH is present in 1000 cc (1 litre) of its solution, the solution is known as decinormal (N/10) solution.
4. What is ECE?
Ans: we have known from Faraday’s 1st Law of electrolysis that the mass or the amount of the ions or the chemical substance deposited at either of the electrodes due to the passage of electricity is directly proportional to the quantity of electricity passed through that solutions.
If m be the mass of substance deposited & Q be the quantity of electricity passed for time “t” seconds.
Thus, the Electro-chemical Equivalent (E.C.E) can be defined as the amount of the ions or the chemical substance in grams deposited at either of the electrodes due to the passage of 1- ampere current for 1 second through the electrolyte solution.
5.Give a chemical reaction to show reaction is first order.
Ans: A reaction is said to be first order when the rate or of the chemical reaction depends upon only one concentration power of the reactant.