The ionization constant of nitrous acid is 4.5 × 10 - 4 . Calculate the p H of 0.04 M sodium nitrite solution and also its degree of hydrolysis.

N a N O 2 is the salt of a strong base N a O H and a weak acid H N O 2 . N O 2 - + H 2 O ⇋ HN O 2 + O H - K h = HN O 2 O H - N O 2 - = HNO 2 OH - [ H + ] NO 2 - [ H + ] ∴ k w = OH - H + = 10 - 14 ; K a = NO 2 - H + HNO 2 ⇒ K h = K w K a = 1 0 - 14 4.5 × 1 0 - 4 = 0.22 × 1 0 - 10 Now, If x moles of the salt undergoes hydrolysis, then the concentration of various species present in the solution will be: N O 2 - = 0.04 - x ≈ ⁡ 0 . 04 HN O 2 = x O H - = x K h = x 2 0.04 = 0.22 × 1 0 - 10 x 2 = 0.0088 × 1 0 - 10 x = 0.093 × 1 0 - 5 ∴ O H - = 0.093 × 1 0 - 5 M H 3 O + = K w H O - = 1 0 - 14 0.093 × 1 0 - 5 = 10.75 × 1 0 - 9 M ⇒ pH = - log ⁡ 10.75 × 1 0 - 9 pH = - [ log ⁡ 10.75 ) + l o g ⁡ ( 1 0 - 9 ] pH = - [ log ⁡ 10.75 ) - 9 l o g 1 0 = 7.96 Therefore, the degree of hydrolysis (h) = x 0.04 = 0 . 093 × 1 0 - 5 0.04 = 2.325 × 1 0 - 5 .

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The compound whose 0.1 M solution is acidic : [pK_a for HCOOH = 3.75, pK_b of NH₄OH = 4.74]

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Important Questions on Ionic Equilibrium

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

The

pH

of ammonium phosphate solution, if

{pk}_{a}

of phosphoric acid and

{pk}_{b}

of ammonium hydroxide are

5.23

and

4.75

respectively, is

EASY

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Arrange the aqueous solutions of the following salts in the increasing order of their $pH$ .

$I . {CuSO}_{4} II . NaCN III . KCl$

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

A weak acid is titrated with a weak base. Consider the following statements regarding the

pH

of the solution at the equivalence point:
(i)

pH

depends on the concentration of acid and base.
(ii)

pH

is independent of the concentration of acid and base
(iii)

pH

depends on the

{pK}_{a}

of acid and

{pK}_{b}

of base.
(iv)

pH

is independent of the

{pK}_{a}

of acid and

{pK}_{b}

of base.
The correct statements are:-

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Given the

{pK}_{a}

of a weak acid

HA

4.60

and

{pK}_{b}

of a weak base

BOH

4.80,

then find the

pH

0.1 M

solution of the salt

BA,

formed from

HA

and

BOH .

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

The

p H

of a

0.02 M

N H_{4} C l

solution will be [Given:

K_{b} (N H_{4} O H) = 10^{- 5}

and

\log 2 = 0.301

]

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

The

{pK}_{b}

of dimethylamine and

{pK}_{a}

of acetic acid are

3.27

and

4.77

respectively at

T (K) .

The correct option for the

pH

of dimethyl ammonium acetate solution is:

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

50 mL

0.02 MNaOH

solution is mixed with

50 mL

0.06 M

acetic acid solution, the

pH

of the resulting solution is_________

(pKa

of acetic acid is

4.76, \log 5 = 0.70)

EASY

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

In the hydrolysis of a salt of weak acid and weak base, the hydrolysis constant

K_{h}

is equal to

EASY

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Which of the following salts will give highest

p H

in water?

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Which among the following salt solutions is basic in nature?

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

20 mL

0.1 M {NH}_{4} OH

is mixed with

40 mL

0.05 M HCl

. The

pH

of the mixture is nearest to:
(Given:

K_{b} ({NH}_{4} OH) = 1 \times 10^{- 5}, \log 2 = 0.30

\log 3 = 0.48, \log 5 = 0.69, \log 7 = 0.84

\log 11 = 1.04

)

EASY

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

The pH of 0.1 M aqueous solution of

N a C l, C H_{3} C O O N a a n d N H_{4} C l

will follow the order:

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Match the following

	List-I		List-II
(A)	$Aq .$ Solution of ${AlCl}_{3}$	(I)	Basic
(B)	$Aq .$ solution of ${CH}_{3} COONa$	(II)	Acidic
(C)	$Aq .$ solution of $KCl$	(III)	Highly conductive
(D)	${Al}_{2} O_{3}$	(IV)	Strongly basic
		(V)	Amphoteric

The correct match is

EASY

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Which of the following statements is correct?

HARD

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

If the

pKa

of lactic acid is

5

, then the

pH

0.005 M

calcium lactate solution at

25 ° C

is __________

\times 10^{- 1}

(Nearest integer)

EASY

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

25^{o} C

, the ionization constant for anilinium hydroxide is

5.00 \times 10^{- 10}

. The hydrolysis constant of anilinium chloride is

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Which of the following salts is the most basic in aqueous solution?

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

{pK}_{a}

of a weak acid

(HA)

and

{pK}_{b}

of a weak base

(BOH)

are

3.2

and

3.4

respectively. The

pH

of their salt

(AB)

solution at

25^{o} C

HARD

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

Do you expect different products in solution when aluminium(III) chloride and potassium chloride treated separately with normal water? Write equations wherever necessary.

MEDIUM

Chemistry>Physical Chemistry>Ionic Equilibrium>Hydrolysis of Salts and pH of their Solutions

The ionization constant of nitrous acid is

4.5 \times 10^{- 4}

. Calculate the

p H

0.04 M

sodium nitrite solution and also its degree of hydrolysis.

The compound whose 0.1 M solution is acidic : [pKa for HCOOH = 3.75, pKb of NH4OH = 4.74]

Important Questions on Ionic Equilibrium

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The compound whose 0.1 M solution is acidic : [pK_a for HCOOH = 3.75, pK_b of NH₄OH = 4.74]