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Standard IX

Chemistry

pH of a Solution

Calculate the...

Question

Calculate the pH of a solution obtained by mixing equal volume of 0.02M HOCl & 0.2M ${C H}_{3} C O O H$ solutions.
Given that $K_{a} (H O C l) = 2 \times 10^{- 4}$ and $K_{a} (C H_{3} C O O H) = 2 \times 10^{- 5}$

3.26

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4.52

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2.7

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1.23

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Solution

The correct option is C 2.7
Whem equal volume volume of $0.02 H H O C l$ and $0.2 M C H_{3} C O O H$ are mixed.
New conc. of $H O C l = \frac{0.02}{2} = 0.01 H$
New conc of $C H_{3} C O O H = \frac{0.2}{2} = 0.1 H$
Now,
For a mixture of weak acids we know
$[H^{+}] = \sqrt{K a_{1} C_{2} + K a_{2} C_{2}}$
$= \sqrt{2 \times 10^{- 4} \times 10^{- 2} + 2 \times 10^{- 5} \times 10^{- 1}}$
$= \sqrt{4 \times 10^{- 6}}$
$= 2 \times 10^{- 3}$
$∴ p h = 3 - {log}^{2}$
$= 2.7$

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Similar questions

Q. Calculate the ratio

\frac{α_{1}}{α_{2}}

of a solution obtained by mixing equal volume of 0.02 M

H O C l

( a weak acid) and 0.2 M

C H_{3} C O O H

solution.
where,

α_{1}

is the degree of dissociation of

H O C l

α_{2}

is the degree of dissociation of

C H_{3} C O O H

Given that:

K_{a_{1}} (H O C l) = 2 \times 10^{- 7}

K_{a_{1}} (C H_{3} C O O H) = 2 \times 10^{- 5}

Q. Calculate the

p H

of solution when

100 mL

0.1 M

C H_{3} C O O H

and

100 mL

0.1 M H C O O H

are mix together (Given :

K_{a} (C H_{3} C O O H) = 2 \times 10^{- 5}, K_{a} (H C O O H) = 6 \times 10^{- 5})

(Given:

log 2 = 0.30

)

Q. Calculate the ratio

\frac{α_{1}}{α_{2}}

of a solution obtained by mixing equal volume of 0.02 M

H O C l

( a weak acid) and 0.2 M

C H_{3} C O O H

solution.
where,

α_{1}

is the degree of dissociation of

H O C l

α_{2}

is the degree of dissociation of

C H_{3} C O O H

Given that:

K_{a_{1}} (H O C l) = 2 \times 10^{- 7}

K_{a_{1}} (C H_{3} C O O H) = 2 \times 10^{- 5}

Q. Calculate

[H^{+}]

of solution obtained by mixing equal volume of 0.02 M

H N O_{2}

( a weak acid) and 0.2 M

C H_{3} C O O H

solution.
Given that:

K_{a_{1}} (H N O_{2}) = 2 \times 10^{- 4}

K_{a_{2}} (C H_{3} C O O H) = 2 \times 10^{- 5}

Where ,

K_{a_{1}} a n d K_{a_{2}}

are the dissociation constants of

H N O_{2} a n d C H_{3} C O O H

respectively.

Q. Calculate

[H^{+}]

of solution obtained by mixing equal volume of 0.02 M

H N O_{2}

( a weak acid) and 0.2 M

C H_{3} C O O H

solution.
Given that:

K_{a_{1}} (H N O_{2}) = 2 \times 10^{- 4}

K_{a_{2}} (C H_{3} C O O H) = 2 \times 10^{- 5}

Where ,

K_{a_{1}} a n d K_{a_{2}}

are the dissociation constants of

H N O_{2} a n d C H_{3} C O O H

respectively.

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Calculate the pH of a solution obtained by mixing equal volume of 0.02M HOCl & 0.2M CH3COOH solutions.Given that Ka(HOCl)=2×10−4 and Ka(CH3COOH)=2×10−5

The correct option is C 2.7Whem equal volume volume of 0.02HHOCl and 0.2MCH3COOH are mixed.New conc. of HOCl=0.022=0.01HNew conc of CH3COOH=0.22=0.1HNow,For a mixture of weak acids we know[H+]=√Ka1C2+Ka2C2=√2×10−4×10−2+2×10−5×10−1=√4×10−6=2×10−3∴ph=3−log2=2.7

Calculate the pH of a solution obtained by mixing equal volume of 0.02M HOCl & 0.2M ${C H}_{3} C O O H$ solutions.
Given that $K_{a} (H O C l) = 2 \times 10^{- 4}$ and $K_{a} (C H_{3} C O O H) = 2 \times 10^{- 5}$