Question

what are the major differences between titration curves of a stong acid and strong base VS. a tiration curve of a weak acid and strong base. explain why the weak acid system behaves differntly then the strong system?

Answer 1

Answer Titration of a strong acid with a strong base Suppose our analy te is hydrochloric acid (Hali (strong acid) and the titrat is sodium hydroxide (NaOH) Estrong base). If we start plotting the pH of the analyte against the volume of Not that we are adding from the burette, we will get a titration curve as shown below PH of the sol analyte .........fm equivalence point solution . edume of titrant added ano. Points: No NaOH is added yet, so the pH of the analyte is low (it predominantly contains 'H₂0² from dissociation of Hel.) " Hel + H₂O - H₂ott í As NaOH is added doopwise, H30't slowly starts getting consumed by OH- produced by dissociation of Naoh. Analyte is still acidie due to predominance of Hoot ions.

Point 2: This is the pH recorded at a time point just before complete neutralization takes place. Point 3: This is the equivalence point . At this point, moles of NaOH added moles of He in the analyte . At this point, H3otions are completely neutralized by otions. The solution only has salt (Nace) and water therefore the pH is neutral ie pH=7 → Nace + H2O at equivalence - point Pointe: Addition of Na OH continues, .ph starts becoming basic because Hel has been completely neutralized and now excess of on ions are present in the soluion NaOH in → Nattoh saj terem atter equivalence an d point Titration of a weak acid with strong base! Let's assume our analyte is acetic acid (CA3 Cook) weak acid and the titrant is sodium hydroxide (NaOH) strong base. It we start plotting the pH of the analyte against the volume of Naot that we

are adding from the burette, we will get a titration curve as shown below. pH of the rol . . 3 . + . . . Requivalence point Analyte solution Volume of Titron't added Point No Nooh added yet, so the pH of the analyte is low fit predominantly contains Hot from dissociation of CH3COOH), But acetic acid is a weak acid, so the starting pH is higher than what we noticed in case of the former one. CH3 W00H + H2O = Ctz 000 + H307 As Nach is added dsopwise, H304 slowly starts getting consumed by OHT, But analyte is still acidie due to pre dominance of thot ions. Point 2: This is the pH recorded at a time point just before complete neutralization takes place

point3: This is the equivalence point. The H307 ions are completly neutralized by otions CH₃COOH + NaOH - CH3 Coona + H2O At equivalence point the sowion contains CH3COONa salt. This dissociates in et300 and Nations. Chacoo is relatively a strong base (weak acid CH₂ cooh has a strong conjugate base) and will this react with H2O to produce Oh on this increasing the ph tong at the equiliilenee point CA COUNG - CH3 400 + Nat 11+20 - The - CH3COOH + oH Point 4: Beyond the equivalence point (when NaOH is in excess) the curve is identical to Hel-NaOH curre as shown below: - pH of the 127 analyte of solution Weak acid strong base strong neid Strong base 55 Volume of Ti toont added