Question dos5. Dissociation constant of NH_cuatroOH is step one.8 x 10 -5 the hydrolysis constant of NH₄Cl would be ……………. (a) 1.8 x 10 -19 (b) 5.55 x 10 -10 (c) 5.55 x 10 -5 (d) 1.80 x 10 -5 Answer: (b) 5.55 x 10 10

• Lewis acid try a species you to accepts an electron partners.
• Lewis acid are a confident ion (or) an electron lacking molecule.
• Example, Fe 2+ , CO₂, BF₃, SiF₄ etc…

• Lewis legs are a types one donates a keen electron partners.
• Lewis ft try a keen anion (or) basic molecule which have atleast one to solitary collection of electrons.
• Example escort service Rockford, NH₃, F – , CH₂ = CH₂, CaO etc….

Question 2. Discuss the Lowry – Bronsted concept of acids and bases. Answer: According to Lowry – Bronsted concept, an acid is defined as a substance that has a tendency to donate a proton to another substance and base is a substance that has a tendency to accept a proton from other substance. When hydrogen chloride is dissolved in water, it donates a proton to the later. Thus, HCl behaves as an acid and H₂O is base. The proton transfer from the acid to base can be represented as HCl + H₂O \(\rightleftharpoons\) H₃O + + Cl –

When ammonia is dissolved in water, it accepts a proton from water. In. this case, ammonia (NH₃) acts as a base and H₂O is acid. The reaction is represented as H₂O + NH₃ \(\rightleftharpoons\) NH₄ + + OH – Let us consider the reverse reaction in the following equilibrium

H₃O + donates a proton to Cl – to form HCI i.e., the products also behave as acid and base. In general, Lowry – Bronsted (acid – base) reaction is represented as Acid₁ + Base₂ \(\rightleftharpoons\) Acid₂ + Base₁ The species that remains after the donation of a proton is a base (Base₁)and is called the conjugate base of the Bronsted acid (Acid₁). Conjugate acid – base pair

HCl and Cl – , H₂O and H₃O are two conjugate acid – base pairs. i.e., Cl_– is the conjugate base of the acid HCl (or) HCl is conjugate acid of Cl – Similarly H₃₂O. Limitations of Lowry – Bronsted theory. Substances like BF₃ , AICl₃ etc., that do not donate protons are known to behave as acids.

1. HS – (aq) + HF \(\rightleftharpoons\) F – (aq) + H₂S (aq)
2. HPO₄ 2- + SO₃ 2- \(\rightleftharpoons\) PO₄ 3- + HSO₃ –
3. NH₄ + + CO₃ 2- \(\rightleftharpoons\) NH₃ + HCO₃ –

O ‘s the conjugate acidic out-of H

• HF and F – , HS – and H₂S are two conjugate acid – base pairs. • F – is the conjugate base of the acid HF (or) HF is the conjugate acid of F – • H₂S is the conjugate acid of HS – (or) HS – is the conjugate base of H₂S.

In other words, chemicals species one disagree only from the good proton have been called conjugate acid – foot pairs

• HPO₄ 2- and PO₄ 3- , SO₃ 2- and HSO₃ – are two conjugate acid – base pairs. .PO₄ 3- is the conjugate base of the acid HPO₄ 2- (or) HPO₄ 2- is the conjugate acid of PO₄. •HSO₃ – is the conjugate acid of SO₃ 2- (or) SO₃ 2- is the conjugate base of HSO₃ – .

• NH + and NH3, CO3 2- and HCO3 – are two conjugate acid-base pairs. • HCO₃ – is the conjugate of acid CO₃ 2- (or) CO₃ 2- is the conjugate bases of HCO₃ – . • NH₃ is the conjugate base of NH₄ + (or) NH₄ + is the conjugate acid of NH₃.