Potentiometric and conductometric titration template

Abitur / university / CBSE: burette over a beaker on a magnetic stirrer, a Pt indicator electrode and a reference electrode wired to a high-resistance voltmeter (redox titration of Fe²⁺); the conductometric version uses a conductivity cell and meter.

What the template shows

• Find the end point from a meter reading instead of an indicator
• Conductometric version
• Dip a conductivity cell (two platinised Pt plates) in the beaker, wired to a conductivity meter. HCl with NaOH: the conductance falls (H⁺ replaced by slower Na⁺), then rises with excess OH⁻; two straight lines cross at the end point. Use titrant about ten times the analyte concentration
• Reference electrode
• Calomel or Ag/AgCl: constant potential
• Fe²⁺ (e.g. Mohr's salt) in dilute H₂SO₄
• Magnetic stirrer
• Stir; read the steady EMF after each addition
• e.g. 0.0167 mol dm⁻³ K₂Cr₂O₇ or 0.1 mol dm⁻³ Ce⁴⁺; 1 cm³ at a time, then 0.1 cm³ near the end point
• Pt indicator electrode
• Its potential follows the Fe³⁺ : Fe²⁺ ratio
• High-resistance voltmeter
• Or a pH meter on mV. Plot EMF against volume: the end point is the steepest rise (largest ΔE/ΔV)
• Reaction setup

Drawn with 26 shapes – every one editable in MolDraw.

Sources

• Atkins, de Paula & Keeler, Atkins' Physical Chemistry, 11th ed., OUP 2018 Textbook