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 .

HARD

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Which of the following aqueous solution of sodium acetate will show minimum $pH$ ?

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Important Questions on Ionic Equilibrium

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:-

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 $pH$ .

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

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

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

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

]

EASY

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

Which of the following statements is correct?

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)

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 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:

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)

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

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 .

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

MEDIUM

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

The ionization constant of ammonium hydroxide is 1.77 x 10^{- 5} at 298 K. Hydrolysis constant of ammonium chloride is :

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.

Which of the following aqueous solution of sodium acetate will show minimum pH?

Important Questions on Ionic Equilibrium

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Which of the following aqueous solution of sodium acetate will show minimum $pH$ ?