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Standard XII

Chemistry

Sulphuric Acid

Given the fol...

Question

Given the following $K_{a}$ values, determine which species is the strongest base.
$H S O_{4}^{-} = 1.2 \times 10^{- 2}, H_{2} P O_{4}^{-} = 6.3 \times 10^{- 8}, H C O_{3}^{-} = 4.7 \times 10^{- 11}$

C O_{3}^{2 -}

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H_{2} S O_{4}

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S O_{4}^{2 -}

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H P O_{4}^{2 -}

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Solution

The correct option is A $C O_{3}^{2 -}$
Greater the value of dissociation constant of the acid ( $K_{a}$ ), more is the strength of the acid. Conjugate base of a weak acid is strong. By given value of $K_{a}$ , it can be seen that $H C O_{3}^{-}$ is weakest acid so its conjugate base is strongest.

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Similar questions

Q. The

K_{a}

values for

H P O_{4}^{2 -}

and

H S O_{3}^{-}

are

4.8 \times 10^{- 13}

and

6.3 \times 10^{- 8}

respectively. Therefore, it follows that

H P O_{4}^{2 -}

is a ____________ acid than

H S O_{3}^{-}

and

P O_{4}^{3 -}

is a ____________ base than

S O_{3}^{2 -}

Identify Bronsted acids in the reaction : $H_{2} C O_{3} + H P O_{4}^{2 -} ⇌ H_{2} P O_{4}^{-} + H C O_{3}^{-}$

H_{2} S O_{4} ⟶ H^{+} + H S O_{4}^{-}

(100% ionisation)

H S O_{4}^{-} ⟶ H^{+} + S O_{4}^{2 -}

(10% ionisation)

The given reaction takes place when sulphuric acid dissolves in water.

If we start with

0.2 M

aqueous solution of

H_{2} S O_{4}

then maximum concentration is of __________ species.

Q. Calculate the equilibrium constants for the reactions with water of

H_{2} P O_{4}^{⊝}, H P O_{4}^{2 -}

and

P O_{4}^{3 -}

as base. Comparing the relative values of two equilibrium constants of

H_{2} P O_{4}^{⊝}

with water, deduce whether solutions of this ion in water are acidic or bases. Deduce whether solutions of

H P O_{4}^{2 -}

are acidic or bases. Given

K_{1}, K_{2}

and

K_{3}

for

H_{3} P O_{4}

are

7.1 \times 10^{- 3}, 6.3 \times 10^{- 8}

and

4.5 \times 10^{- 13}

respectively .

When sulphuric acid dissolves in water, the following reactions take place:

H_{2} S O_{4} ⟶ H^{+} + H S O_{4}^{-}

(

100 %

ionisation)

H_{2} S O_{4}^{-} ⟶ H^{+} + S O_{4}^{2 -}

(

10 %

ionisation)

We start with

0.2 M

aqueous solution of

H_{2} S O_{4}

The species that has the maximum concentration is :

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Given the following Ka values, determine which species is the strongest base.HSO−4=1.2×10−2, H2PO−4=6.3×10−8, HCO−3=4.7×10−11

The correct option is A CO2−3Greater the value of dissociation constant of the acid (Ka), more is the strength of the acid. Conjugate base of a weak acid is strong. By given value of Ka, it can be seen that HCO−3 is weakest acid so its conjugate base is strongest.

Given the following $K_{a}$ values, determine which species is the strongest base.
$H S O_{4}^{-} = 1.2 \times 10^{- 2}, H_{2} P O_{4}^{-} = 6.3 \times 10^{- 8}, H C O_{3}^{-} = 4.7 \times 10^{- 11}$

The correct option is A $C O_{3}^{2 -}$
Greater the value of dissociation constant of the acid ( $K_{a}$ ), more is the strength of the acid. Conjugate base of a weak acid is strong. By given value of $K_{a}$ , it can be seen that $H C O_{3}^{-}$ is weakest acid so its conjugate base is strongest.