pH and Buffer Solutions

1) Calculate the pH of
(a) 0.1 mol/ litre HCL

(b) 0.1 mol/ litre KOH

(c) 10 mmol/ litre HCL

2) Calculate the hydrogen ion concentretion of blood plasma, pH 7.42. What will
be the pH in acidosis if this hyodrogen ion concentration is doubled?
(Hint: Plamsa pH= -log10 [H+] )

3) A solution is prepared by dissolving sodium benzoate and benzoic acid in
water to give a 9 mmol/ litre concentration of each compound. The mixture has a
pH of 4.21 at 25℃. Calculate the acid dissociation constant of benzoic acid.
(Hint: pH= pKa + log10 × [sodium benzoate] ÷ [benzoic acid]