Answer :
(1) pH = 1.27
(2) pH = 13.35
(3) The given solution is not a buffer.
Explanation :
(1) 53.1 mM HCl
Concentration of HCl = [tex]53.1mM=53.1\times 10^{-3}M[/tex]
As HCl is a strong acid. So, it dissociates completely to give hydrogen ion and chloride ion.
So, Concentration of hydrogen ion= [tex]53.1\times 10^{-3}M[/tex]
pH : It is defined as the negative logarithm of hydrogen ion concentration.
[tex]pH=-\log [H^+][/tex]
[tex]pH=-\log (53.1\times 10^{-3})[/tex]
[tex]pH=1.27[/tex]
(2) 0.223 M KOH
Concentration of KOH = 0.223 M
As KOH is a strong base. So, it dissociates completely to give hydroxide ion and potassium ion.
So, Concentration of hydroxide ion= 0.223 M
Now we have to calculate the pOH.
[tex]pOH=-\log [OH^-][/tex]
[tex]pOH=-\log (0.223)[/tex]
[tex]pOH=0.65[/tex]
Now we have to calculate the pH.
[tex]pH+pOH=14\\\\pH=14-pOH\\\\pH=14-0.65=13.35[/tex]
(3) 53.1 mM HCl + 0.223 M KOH
Buffer : It is defined as a solution that maintain the pH of the solution by adding the small amount of acid or a base.
It is not a buffer because HCl is a strong acid and KOH is a strong base. Both dissociates completely.
As we know that the pH of strong acid and strong base solution is always 7.
So, the given solution is not a buffer.
