HCN being a weak acid has low ionization constant,

C = 0.1 M

pH = 5.2

thus [H⁺] = 10 ^{- 5.2} = 0.1 I_c

I_c= 6.3 x 10 ^-5

now, K_a = Ic ² x C [ for weak acid ]

=( 6.3 x 10 ^-5 )² x 0.1

= 3.98 x 10 ^-10

HNO₃ ------------> H⁺ + NO₃^-

given,

concentration of acid = 0.04 N = 0.04 M

thus, [H⁺] = 0.04 M

pH = - log [ 0.04 ]

= - log [ 0.04 ]

= 1.39

For weakly soluble electrolytes which gives less ions when dissolved in water the solubility product is the product of concentrations of ions expressed in terms of molarity produced during the ionization of the electrolyte.

its value is very less ( < 10^-5).

CaF2 -----------> Ca⁺⁺ + F2-

[ Ca++ ] = 2.94 x 10 ^-4

2 [ F- ] = 2 x 2.92 x 10 ^-4

thus , Ksp = [ Ca⁺⁺] [ 2F^-]²

= 4 x 2.94 x 10 ^-4 x ( 2.94 x 10 ^-4) ²

= 1.01 x 10 ^-10

given,

pH = 10

i.e. - log [ H⁺] = 10

thus, [H⁺] = 1 x 10 ^-10

we know, [H⁺] [OH^-] = 10 ^-14

SO, [OH-] = 1 X 10 ^-4 mole/litre

Given,

pH of NaOH is 11

i.e. - log [ H+ ] = 10^-11

thus, [OH-] = 10 ^-14 / 10 ^-11

= 10 ^-3 mole/liter

molecular weight of NaOH is 40 g/mole

thus, in the strength is g/liter = 40 x 10 ^-3

= 0.04 g/liter

NaOH ------> Na+ + OH-

given, [NaOH] = 0.4 g/liter

molecular mass of NaOH is 40 g/mol.

thus, Molarity of the solution = 0.4 / 40

=1/100 = 10^-2mole/liter

now, from the dissociation pattern of NaOH

[NaOH] = [OH-] = 10^-2

thus, pOH = -log [OH-]

= 2

thus, pH = 14 - pOH

= 12

It is a measure for strength of electrolytes, the electrolytes which have degree of ionization nearly equal to 1 are strong, else are weak.

It is the representation of ratio of molecules disassociated ions to the total number of molecules when put in water. its range is [0,1].

The phenomena of suppressing the ion concentration or ionic product of a weak electrolyte by a stronger electrolyte when they yield at least a common ion together in a solution is called common ion effect.

eg, When HCN is mixed in water with HCl , the ionic product of HCN is suppressed.

the mathematical expression representing the variation of the degree of dissociation with dilution for weak electrolytes is called OStwald's dilution law.

mathematical exp, K = I_d ²/ (1-I_d ) V

according to Bronsted and Lowry,

Any chemical species capable of donating a proton [H+] when dissolved in water is an acid.

Any chemical species capable of accepting proton [H+], which has a lone pair of electrons to make a bond with [H+] is a base.

A Lewis acid is any substance, such as the H⁺ion, that can accept a pair of nonbonding electrons.

A Lewis base isany substance, such as the OH^-ion, that can donate a pair of nonbonding electrons.

Electron pair acceptor are acid and donating are bases.

Limitations of Ostwald's Dilution law are :

• Applicable only for weak electrolytes
• Applicable only for highly diluted solutions
• Assumption is made for 1- I_cto be equal to 1 being I_cvery low for making calculations simpler but this assumption can alter the exact data.

Here , [H+] for acid is < 10 ^-7 { which is not possible }

so,

total [H+] = 10 ^-7 + 10 ^-9

= 1.01 x 10 ^-7

Thus, pH = - log [H+]

= 6.99