← Labs|Titration Simulator — Real S-Curve with Equivalence Point Detection
Titration Type
Burette Control
Added: 0.00 mLMax: 55.0 mL
Setup
Analyte:25 mL 0.1M HCl
Titrant:0.1M NaOH
EP vol:25.00 mL
EP pH:7.00
Indicator:Phenolphthalein (8.2–10)
Current pH
1.00
Strongly acidic
Vol: 0.00 mL
0% to EP
Description
Sharpest equivalence point. pH jumps ≈4→10 over 0.05 mL near EP.
Burette
Titration Curve (pH vs Volume of Titrant added)
Titration Theory
pH Formulas
Strong acid: pH = −log[H⁺]
Weak acid: pH = ½(pKa − log Ca)
Buffer (H-H): pH = pKa + log([A⁻]/[HA])
Salt of WA+SB: pH = 7 + ½pKa
Salt of SA+WB: pH = 7 − ½pKb
Equivalence Point
SA + SB: pH = 7 exactly
WA + SB: pH > 7 (conjugate base hydrolysis)
SA + WB: pH < 7 (conjugate acid hydrolysis)
WA + WB: pH ≈ 7 + ½(pKa − pKb)
Half-Equivalence Point
At ½ EP for WA + SB:
[HA] = [A⁻]
∴ pH = pKa (simplest!)
For SA + WB:
pOH = pKb
∴ pH = 14 − pKb
Indicators
Phenolphthalein: 8.2–10 (colourless→pink)
Methyl orange: 3.1–4.4 (red→yellow)
Methyl red: 4.4–6.2
Bromothymol blue: 6.0–7.6
Universal: full pH range
Buffer Capacity
Maximum buffer capacity at pH = pKa
(equal moles HA and A⁻)
Buffer range: pKa ± 1
Choose buffer whose pKa ≈ desired pH
Degree of Hydrolysis
h = √(Kh/C)
Kh = Kw/Ka (for anion)
Kh = Kw/Kb (for cation)
Higher Kh → more hydrolysis → greater pH shift from 7