The percentage deprotonation of a 0.115 M solution of benzoic acid (a weak, monoprotic acid) is 2.1%. What is the pH of the solution

Respuesta :

Answer:  pH of the solution is 2.6

Explanation:

[tex]HA\rightarrow H^+A^-[/tex]

 cM              0             0

[tex]c-c\alpha[/tex]        [tex]c\alpha[/tex]           [tex]c\alpha[/tex]

So dissociation constant will be:

[tex]K_a=\frac{(c\alpha)^{2}}{c-c\alpha}[/tex]

Give c= 0.115 M and [tex]\alpha[/tex] = [tex]\frac{2.1}{100}=0.021[/tex]

[tex](\alpha)=0.030[/tex]

[tex][H^+]=c\times \alpha[/tex]

[tex][H^+]=0.115\times 0.021=0.0024[/tex]

Also [tex]pH=-log[H^+][/tex]

[tex]pH=-log[0.0024]=2.6[/tex]

Thus pH of the solution is 2.6

The pH value of the solution is  : 2.6

Given data:

percentage deprotonation = 2.1%

concentration of solution ( c )  = 0.115 M

Determine the pH of the solution

Applying dissociation constant ;  K[tex]_{a}[/tex] = [tex]\frac{(c\alpha)^{2} }{c-c\alpha }[/tex]       ( HA ---> H⁺A⁻ )

∝ = [tex]\frac{2.1}{100}[/tex] = 0.021

[ H⁺ ] = c * ∝ = 0.115 * 0.021 = 0.0024

Given that

pH = -log [ H⁺ ]

pH = - log [ 0.0024 ]

∴ pH of the solution = 2.6

Hence we can conclude that the pH of the solution is 2.6

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