Three reactions involving H2PO-4 are given-i H2PO4-H2O- H3O-H2P O -4ii H2P O -4-H2O- HPO2-4-H3O-iii H2P O -4-OH- H3PO4-O2-In which of the given does H2P O -4 act as n acid-

The correct option is B (ii) only(i) H_2PO_4+H_2O→ H_3O^++H_2P O ^ _4 (ii) H_2P O ^ _4+H_2O→ HPO^2 _4+H_3O^+ (iii) H_2P O ^ _4+OH^ → H_3PO_4+O^2 ...

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Byju's Answer

Standard XII

Chemistry

Arrhenius Acid

Three reactio...

Question

Three reactions involving $H_{2} P O_{4}^{-}$ are given?
(i) $H_{2} P O_{4} + H_{2} O \to H_{3} O^{+} + H_{2} P O_{4}^{-}$
(ii) $H_{2} P O_{4}^{-} + H_{2} O \to H P O_{4}^{2 -} + H_{3} O^{+}$
(iii) $H_{2} P O_{4}^{-} + O H^{-} \to H_{3} P O_{4} + O^{2 -}$
In which of the given does $H_{2} P O_{4}^{-}$ act as n acid?

(i) only

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(ii) only

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(i) and (ii)

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(iii) only

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Solution

The correct option is B (ii) only
(i) $H_{2} P O_{4} + H_{2} O \to H_{3} O^{+} + H_{2} P O_{4}^{-}$
(ii) $H_{2} P O_{4}^{-} + H_{2} O \to H P O_{4}^{2 -} + H_{3} O^{+}$
(iii) $H_{2} P O_{4}^{-} + O H^{-} \to H_{3} P O_{4} + O^{2 -}$
In the above equations only in the second equation $H_{2} P O_{4}^{-}$ donotaed protons to $H_{2} O$ and acts as acid (proton donor ( $H^{+}$ donor is acid).
Hence option B is correct.

Suggest Corrections

Similar questions

Q. Three reactions involving

H_{2} P O_{4}^{-}

are given below.
I.

H_{3} P O_{4} + H_{2} O \to H_{3} O^{+} + H_{2} P O_{4}^{-}

II.

H_{2} P O_{4}^{-} + H_{2} O \to H P O_{4}^{2 -} + H_{3} O^{+}

III.

H_{2} P O_{4}^{-} + O H^{-} \to H_{3} P O_{4} + O^{2 -}

In which of the above does

H_{2} P O_{4}^{-}

act as an acid?

Q. The hydrolysis constant

K_{H}

for the reaction

H_{2} P O_{4}^{-} + H_{2} O \to H_{3} P O_{4} + O H^{-}

1.4 \times 10^{- 12}

. The ionisation constant for

H_{3} P O_{4} + H_{2} O \to H_{2} P O_{4}^{-} + H_{3} O^{+}

is:

Q. Equivalent weight of

H_{3} P O_{4}

in each of the reaction will be respectively:

H_{3} P O_{4} + O H^{-} \to H_{2} P O_{4}^{-} + H_{2} O

H_{3} P O_{4} + 2 O H^{-} \to H P O_{4}^{2 -} + 2 H_{2} O

H_{3} P O_{4} + 3 O H^{-} \to P O_{4}^{3 -} + 3 H_{2} O

Q. Calculate the pH of

0.1

M solution of (i)

N a H C O_{3}

, (ii)

N a_{2} H P O_{4}

and (iii)

N a H_{2} P O_{4}

Given that:

C O_{2} + H_{2} O ⇌ H^{+} + C O_{3}^{2 -}

;

K_{1} = 4.2 \times 10^{- 7}

H C O_{3}^{-} ⇌ H^{+} + C O_{3}^{2 -}

;

K_{2} = 4.8 \times 10^{- 11}

H_{2} P O_{4} ⇌ H^{+} + H_{2} P O_{4}^{-}

;

K_{1} = 7.5 \times 10^{- 3}

H_{2} P O_{4}^{-} ⇌ H^{+} + H P O_{4}^{2 -}

;

K_{2} = 6.2 \times 10^{- 8}

H P O_{4}^{2 -} ⇌ H^{+} + P O_{4}^{3 -}

;

K_{3} = 1.0 \times 10^{- 12}

Q. Conjugate base of

H_{2} P O_{4}^{-}

is:

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Three reactions involving H2PO−4 are given?(i) H2PO4+H2O→H3O++H2PO−4(ii) H2PO−4+H2O→HPO2−4+H3O+(iii) H2PO−4+OH−→H3PO4+O2−In which of the given does H2PO−4 act as n acid?

The correct option is B (ii) only(i) H2PO4+H2O→H3O++H2PO−4(ii) H2PO−4+H2O→HPO2−4+H3O+(iii) H2PO−4+OH−→H3PO4+O2− In the above equations only in the second equation H2PO−4 donotaed protons to H2O and acts as acid (proton donor (H+ donor is acid).Hence option B is correct.