One mole of ammonia was completely absorbed in one litre solution each of (I) 1M HCl, (II) 1M CH3COOH and (III) 1M H2SO4 at 298 K. The decreasing order for the pH of the resulting solutions (Given Kb(NH3) = 4.74)

Question

One mole of ammonia was completely absorbed in one litre solution each of (I) 1M HCl, (II) 1M CH3COOH and (III) 1M H2SO4 at 298 K. The decreasing order for the pH of the resulting solutions (Given Kb(NH3) = 4.74) (A) I > II > III (B) III > II >I (C) II > III >I (D) II > I > III

Tardigrade Admin · Accepted Answer

Acids which are weak in water will be highly acidic in

N H_{3}

(a)

H Cl + N H_{3} ⇌ N H_{4} Cl

(b)

C H_{3} COO H + N H_{3} ⇌ C H_{3} COON H_{4}

(c)

H_{2} S O_{4} + N H_{3} ⇌ (N H_{4})_{2} S O_{4}

∴

Effect of ammonia is least in

H_{2} S O_{4}

and maximum in

C H_{3} COO H

.

∴

Order of acidic strength of resulting solution is

(N H_{4})_{2} S O_{4} > N H_{4} Cl > C H_{3} COON H_{4}

∴

Order of

p H

of resulting solution is

C H_{3} COON H_{4} > N H_{4} Cl > (N H_{4})_{2} S O_{4}

Hence, correct option is II

> I > III

Q. One mole of ammonia was completely absorbed in one litre solution each of (I) 1MHCl, (II) 1MCH3​COOH and (III) 1MH2​SO4​ at 298K. The decreasing order for the pH of the resulting solutions (Given Kb​(NH3​) = 4.74)

I > II > III

III > II >I

II > III >I

II > I > III

Q. One mole of ammonia was completely absorbed in one litre solution each of
(I) $1 M H Cl$ ,
(II) $1 M C H_{3} COO H$ and
(III) $1 M H_{2} S O_{4}$ at $298 K$ .
The decreasing order for the pH of the resulting solutions
(Given $K_{b} (N H_{3})$ = 4.74)