Chemistry Ch.#11

Wisdom Academy

Chemistry

Ch. # 11

11.1

i. Why and how carbon complete its octet?

Ans. Carbon complete its octet to achieve stability. And it complete its octet by completing its tetra-valency.

ii. Point out the properties of carbon which are responsible for the formation of long chains of carbon atom in organic compounds?

Ans. These properties are:

1.      Catenation.

2.      Isomerism.

3.      Strength of covalent bonds of carbon

4.      Multiple Bonding.

iii. Why the melting and boiling points of organic compounds is low?

Ans. The melting and boiling point of organic compounds is low because, covalent bond is present b/w them. It is a very weak bond.

iv. Why the organic compounds are poor conductor of electricity?

Ans. Organic compounds are poor conductor of electricity because covalent bonding is present b/w them and they do not forms ions in water. So, they are poor conductor.

v. What are the reasons for the formation of millions of organic compound?

Ans. The main reasons for the formation of millions of organic compound is isomerism, catenation, strength of covalent bonds in carbon and multiple bonding. These properties are not present in in-organic compounds. They are the cause of formation of many organic compounds.

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Chemistry Ch.# 10

Wisdom Academy

Chemistry

Chapter 10

10.1

i. What is the difference b/w Arrhenius and Bronsted-Lowry base?

Ans. According to Arrhenius Base is a compound which gives hydroxide ions (OH^-) in its aqueous solution. The general equation is:

           BOH_(aq)    ⥨   B⁺_(aq)    +    OH^-_(aq)

         According to Bronsted-Lowry concept “A base is a substance that can accept proton (H⁺) from another substance. The equation is:

         HCl_(aq)     +   NH_3(aq)(Base)     ⥨   NH_4­⁺_(aq)      +     Cl^-_(aq)

ii. What do you mean by neutralization reaction according to Arrhenius acid-base concept?

Ans. When acid reacts with base it forms water and salt it is called neutralization according to Arrhenius Acid-Base concept.

For Example:

     HCl    +    NaOH    ⟶   NaCl   +   H₂O

iii. Prove that water is an amphoteric specie?

Ans. Water is an Amphoteric specie because it act as both acid and base.

As an Acid:

             H₂O        +    NH₃         ⥨       NH₄⁺      +    OH^-

As a Base:

             HCl       +     H₂O       ⥨         H₃O⁺        +         Cl^­-

iv. How can you justify that NH₃ is Bonsted-Lowry base but not Arrhenius base?

Ans. According to Bronsted-Lowry Base is a substance which can accept a proton (H⁺) from another substance. But according to Arrhenius concept Base is a substance which gives hydroxide ions when dissociates in a aqueous solution. NH₃ does not gives hydroxide ions in aqueous solution but it accept a proton from another substance. So, it is a Bronsted-Lowry base but not a Arrhenius Base.

v. State and explain neutralization reaction according to Lewis Concept?

Ans. According to Lewis concept neutralization reaction is a reaction  in which donation and acceptance of an electron pair takes place to form a coordinate covalent bond in an adduct.

                               NH₃ + BF₃  ⟶ [NH₃⟶BF₃]

vi. Define and give the characteristics of Lewis Acid?

Ans. According to Lewis “acid is a substance which can accept a pair of electron”.

1)   Lewis acid is a substance which accept a pair of electron.

2)  Lewis Acid form a coordinate covalent bond with other substance in order to accept a pair of electron.

vii. Why BF₃ act as Lewis Acid?

Ans. BF₃ acts as Lewis Acid because it accept a pair of electron from another substance which act as Lewis Base.

For Example:

               NH₃    +    BF₃  ⟶  [NH₃⟶BF₃]

Here BF₃ accept two electrons and act as Lewis Acid.

Viii. Water is an amphoteric specie according to Bronsted-Lowry concept. What is its nature according to Lewis Concept?

Ans. According to Lewis concept Water act as  Base. Because it gives a pair of electron to hydrogen ion H⁺ and becomes hrdronium ion H₃O⁺.

                 H⁺     +       H₂O     ⟶   [H₃O]⁺

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Chemistry ch.#09

Wisdom Academy

Chemistry

Chapter # 09

Test yourself Answers:

9.1

i.       Why reversible reactions never complete?

Ans. In reversible reactions the products recombine to form reactants and this process keep on continuing. Therefore reversible reactions never go to completion.

ii.     What is static equilibrium, explain with an example?

Ans. Static equilibrium is a state in which the reaction ceases (stop) to proceed. This phenomena is usually applicable in physical phenomena not in chemistry.

For Example:

A hanging picture on wall never falls down because all the forces acting on it are equal and the net force is zero etc.

iii.    Why the amounts of reactants and products do not change in reversible reaction?

Ans. The amount of products and reactants do not change in reversible reaction because the amount of substance changing into reactants from products is equal to the amount of substance changing from reactants to products. Therefore the amount of products and reactants remain constant in reversible reaction.

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