Salt of Weak ...

Salt of Weak Acid and Weak Base

Trending Questions

Q. Find the

p H

of an equimolar solution of

H C N

and

N H_{4} O H

.
Given:

K_{a} (H C N) = 6 \times 10^{- 10}

K_{b} (N H_{4} O H) = 1.8 \times 10^{- 5}

8.45
4.74
12.5
9.24

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Q. What will be the

p H

of an aqueous solution of

0.1 M

ammonium formate

25^{o} C

Given : p K_{a} (H C O O H) = 3.8 a n d p K_{b} (N H_{4} O H) = 4.8

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Q. Consider a weak monobasic acid

H A

having a concentration C with degree of dissociation,

α << 1.

. The pH of this weak acid in terms of acid dissociation constant

K_{a}

and concentration

C

is :

$- l o g_{10} (\sqrt{\frac{K_{a}}{C}})$
$- l o g_{10} \sqrt{K_{a} . C}$
$p H = - l o g_{10} \sqrt{K_{a} . C^{2}}$
$p H = - l o g_{10} \sqrt{K_{a}^{2} . C}$

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An aqueous solution of ammonium acetate is

Faintly acidic
Faintly basic
Fairly acidic
Almost neutral

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Q. Find the

p H

of an equimolar solution of

H C N

and

N H_{4} O H

.
Given:

K_{a} (H C N) = 6 \times 10^{- 10}

K_{b} (N H_{4} O H) = 1.8 \times 10^{- 5}

8.45
4.74
12.5
9.24

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Q. Given the

K_{a}

for acetic acid is

1.77 \times 10^{- 5}

and

K_{b}

for ammonium hydroxide is

1.82 \times 10^{- 5}

.
Calculate the pH of an aqueous solution of ammonium acetate

(C H_{3} C O O N H_{4})

25^{\circ} C

8.115
8.05
7.01
7.65

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An aqueous solution of ammonium acetate is

Faintly acidic
Faintly basic
Fairly acidic
Almost neutral

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The degree of hydrolysis of ammonium acetate is related to its hydrolysis constant by the expression

$a$ = $\frac{K h}{(1 + K h)}$
$a$ = $\frac{K h}{(1 + K h^{2})}$
$a$ = $\frac{\sqrt{K h}}{(1 + \sqrt{K h})}$
$a$ = $\sqrt{\frac{K h}{(1 + K h)}}$

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p K_{a}

of a weak acid (HA) and

p K_{b}

of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is:

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Q. Which of the following mixtures can act as a buffer if equal amount of both species is mixed?

$H C N + N a C N$
$H C O O H + N a O H$
$N H_{4} O H + (N H_{4})_{2} S O_{4}$
(a) and (c) above.

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p K_{a}

of a weak acid (HA) and

p K_{b}

of a weak base (BOH) are 3.2 and 3.4. respectively. The pH of their salt (AB) solution is

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Q. Which of the following statement is correct regarding an eqiumolar solution of a weak acid

C H_{3} C O O H

and a weak base

N H_{4} O H

25^{\circ} C

Higher the concentration of $C H_{3} C O O H$ , lesser is the $p H$ value.
Higher the concentration of $N H_{4} O H$ , higher is the $p H$ value.
$p H$ does not depend on the concentration of $C H_{3} C O O N H_{4}$ .
None of the above

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Q. The dissociation constants for aniline, acetic acid and water at

25^{\circ} C

are

4 \times 10^{- 10}, 2 \times 10^{- 5}

and

10^{- 14}

respectively. Calculate degree of hydrolysis of aniline acetate in a decinormal solution.

0.53
0.15
0.35
0.45

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Q. What will be the

p H

of an aqueous solution of

0.1 M

ammonium formate

25^{o} C

Given : p K_{a} (H C O O H) = 3.8 a n d p K_{b} (N H_{4} O H) = 4.8

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Q. Which of the following describes the correct relation for

p O H

for an aqueous salt solution of weak acid and weak base at

25^{\circ} C ?

$p O H = 14 - \frac{1}{2} (p K_{a} - p K_{b})$
$p O H = 7 + \frac{1}{2} (p K_{a} - p K_{b})$
$p O H = 7 - \frac{1}{2} (p K_{a} - p K_{b})$
$p O H = 14 + \frac{1}{2} (p K_{a} - p K_{b})$

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Q. Which of the following describes the correct relation for hydrolysis constant

(K_{h})

for a salt of weak acid and weak base at

25^{\circ} C ?

$K_{h} = \frac{K_{w}}{K_{a} \times K_{b}}$
$K_{h} = \frac{K_{a}}{K_{w} \times K_{b}}$
$K_{h} = \frac{K_{a} \times K_{b}}{K_{w}}$
$K_{b} = \frac{K_{h}}{K_{a} \times K_{w}}$

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pOH = 7 - 0.5 p K_{a} + 0.5 p K_{b}

is true for an aqueous solution that has which pair of cations and anions amongst the following?

$C_{6} H_{5} N H_{3}^{+}, C H_{3} C O O^{-}$
$N H_{4}^{+}, F^{-}$
$N a^{+}, C H_{3} C O O^{-}$
$N H_{4}^{+}, C l^{-}$

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