Q: A weak acid HX has the dissociation constant 1\times { 10 }^{ -5 }M , It forms a salt NaX in reaction with alkali. The degree of hydrolysis of 0.1M solution if NaX is:

{ X }^{ - }+{ H }_{ 2 }O\rightleftharpoons HX+{ OH }^{ - } { K }_{ h }=\cfrac { { 10 }^{ -14 } }{ { 10 }^{ -5 } } So, degree of hydrolysis x=\sqrt { \cfrac { { K }_{ h } }{ C } } =\sqrt { \cfrac { { 10 }^{ -9 } }{ { 10 }^{ -1 } } } ={ 10 }^{ -4 } % degree of hydrolysis ={ 10 }^{ -4 }\times 100=0.01

Q: The Bronsted acid which gives the weakest conjugate base is:

Strongest acid \rightarrow Weakest conjugate baseAcidity increases across a period and down the group. \therefore HCl is the strongest acidic and Cl^{-} is weakest conjugate base.

Question 1

A weak acid  HX  has the dissociation constant  1	imes { 10 }^{ -5 }M , It forms a salt  NaX  in reaction with alkali. The degree of hydrolysis of  0.1M  solution if  NaX  is:

Accepted Answer

{ X }^{ - }+{ H }_{ 2 }Oightleftharpoons HX+{ OH }^{ - } { K }_{ h }=\cfrac { { 10 }^{ -14 } }{ { 10 }^{ -5 } }  So, degree of hydrolysis x=\sqrt { \cfrac { { K }_{ h } }{ C }  } =\sqrt { \cfrac { { 10 }^{ -9 } }{ { 10 }^{ -1 } }  } ={ 10 }^{ -4 } % degree of hydrolysis  ={ 10 }^{ -4 }	imes 100=0.01

Question 2

In the aqueous solution of sodium acetate the ion that undergoes hydrolysis is :

Accepted Answer

In  CH_{3}COO  Na CH_{3}COO^{-}  undergoes  hydrolysis  as   CH_{3}COOH    is  a  weak  acid while  Na^{+}  does not undergo hydolysis as NaOH is strong base

Question 3

An aqueous solution of salt is alkaline. This shows that salt is made from:

Accepted Answer

Solution of salt is alkaline means cation will not hydrolyze, since it is the cation of a strong base, and the anion will hydrolyze as it is an anion of a weak acid.Option D is correct.

Question 4

If the solubility of  Ag_{2}CrO_{4}  is  S  mole/lit. Then its solubility product is:

Accepted Answer

Ag_{2}CrO_{4}(s) \Leftrightarrow 2Ag^{+} + CrO_{4}^{2-}                                 2S              S K_{sp}= [Ag^+]^{2}	imes [CrO_4^{2-}] K_{sp}= (2S)^{2}	imes S = 4S^3 Hence, option C is correct.

Question 5

The solubility product of NaCl is  2.5 	imes 10^{-9}    moles^{2}/lit^{2} . Its solubility is:

Accepted Answer

K_{sp} = s^{2} =>  s = \sqrt{K_{sp}} = 5*10^{-5}

Question 6

p{H}  of  Ba\left ( OH \right )_{2}  solution is 12. Its solubility product is :

Accepted Answer

Given:  pH=12 Hence,  pOH=14-pH=14-12=2  or  [OH^-]=10^{-2}M . [Ba^{2+}]=0.5 	imes[OH^-]=0.5 	imes10^{-2}M .The expression for the solubility product of barium hydroxide is, K_{sp}=[Ba^{2+}][OH^-]^2=(0.5 	imes10^{-2})(1 	imes10^{-2})^2=5 	imes10^{-7}  .

Question 7

In the reaction,  {HCO_{3}}^{-}+H_{2}O\rightarrow OH^{-}+H_{2}CO_{3} , the conjugate acid - base pair is:

Accepted Answer

A conjugate base is the species formed after an acid donates its proton. Species formed after accepting  H^+  into a base are called conjugate acids. HCO_{3}^{-}+H^{+}	o H_{2}CO_{3} Base                      Conjugate acid

Question 8

The conjugate acid of  OH^{-} is:

Accepted Answer

According to Bronsted Lowry acid-base theory, ''anything which accepts hydrogen ion is a base and anything which donates a hydrogen ion is an acid'' The conjugate acid of a base is the substance that gains a hydrogen ion to form that base. In other words:  OH^- +  H^+   \longrightarrow   H_2O  The conjugate acid of  OH^-  is  H_2O  because when  OH^-  gains a hydrogen ion, it forms  H_2O

Question 9

The Bronsted acid which gives the weakest conjugate base is:

Accepted Answer

Strongest acid  ightarrow  Weakest conjugate baseAcidity increases across a period and down the group. 	herefore   HCl  is the strongest acidic and  Cl^{-}  is weakest conjugate base.

Equilibrium