(a)

(i) HCl + H₂O -----> Cl^- + H₃O

(ii) NH₃ + H₂O -----> NH₄⁺ + OH^-

(iii) The stronger an acid, the weaker its conjugate base. Cl^- is a poor proton acceptor.

(iv) The weaker the base, the stronger its conjugate acid. NH₄⁺ is a good proton donor.

(b)

(i) K_w = [H₃O⁺] x [OH^-]

(ii) The value of K_w increases as the temperature increases; therefore, the equilibrium moves forward, indicating an endothermic reaction (energy absorbed to break bonds).

(iii)

(iv) At 37^o K_w = 2.4 x 10¹⁴

(v)

K_w = [H3O][OH-] = 2.4 x 10^-14

[H₃O] = [OH^-]

[H₃O]² = 2.4 x 10^-14

[H₃O] = √2.4 x 10^-14

[H₃O] = 1.549 x 10^-7

(vi)

pH = −log₁₀ [ H₃O⁺]

6.77 = −log₁₀ [H₃O⁺]

Antilog −6.77 = [H₃O⁺]

1.698 x 10^-7 = [H₃O⁺]

[H₃O⁺] = [OH^-]

K_w = [H₃O ⁺][ OH^-]

K_w = 1.698 x 10^-7 x 1.698 x 10^-7

K_w = 2.883 x 10^-14

Temperature = 40 ^oC