The ionization constant of chloroacetic acid is 1.35xx10^(-3) . What will be pH of 0.1 M acid and its 0.1 M sodium salt solution.

The ionization constant of chloroacetic acid is 1.35xx10^(-3) . What w

1.	The ionization constant of chloroacetic acid is 1.35xx10^(-3) . What will be pH of 0.1 M acid and its 0.1 M sodium salt solution.
Answer» Solution :(i)PH of ACID solution `[H^+]=sqrt(K_axxc)` `K_a=1.35xx10^(-3),c=0.1` M `[H^+]=sqrt(1.35xx10^(-3)xx0.1)` `=sqrt(1.35xx10^(-4))=1.16xx10^(-2)` `pH=-log [H^+]` `=-log (1.16xx10^(-2))` =2-0.064 =1.936 (ii)pH of 0.1 M sodium salt solution. Sodium salt of chloro acetic acid is salt of WEAK acid and strong base. HENCE, `pH=1/2[pK_w+pK_a+logc]` `K_a=1.35xx10^(-3)` `pK_a=-log K_a` `=-log (1.35xx10^(-3))` =-(0.1303-3)=2.8697 `pK_w=-log 10^(-14)` =14 c=0.1 M, log c = log (0.1)=-1 `pH=1/2[14+2.8697-1]` =7.935.