A thermometric titration finds the end point from heat alone: the temperature climbs while the alkali is being neutralised and falls once it has all gone. By hand, pipette the sodium hydroxide into the cup, run the acid in from the burette in portions, stir with the thermometer and read the highest temperature each time. Then draw a curve and a line to the corner, and work out the concentration and ΔHneut. Every attempt uses a different concentration. Allow about 45 minutes.
Checked: Cambridge 9701 Paper 3, February/March 2023 to May/June 2026. Only the papers in our collection are listed, so the real number may be higher. Question papers are available from Cambridge.
This workout needs JavaScript.
25.0 cm³ pipetted to the line, the initial burette reading and every total volume to 0.05 cm³, every temperature to 0.1 °C, headings with units, readings that match your burette and thermometer, and a reading at every volume in the method.
A smooth curve through the rising points and a straight best-fit line through the points after the maximum, extended to meet; the volume and temperature read at the intersection, ΔT from the initial temperature, and two accuracy marks for an end point close to the true value.
Moles of sulfuric acid at the end point, moles and concentration of sodium hydroxide (3 significant figures), q = m c ΔT with the mass of the whole mixture, and ΔHneut per mole of water with a negative sign.
The percentage error in ΔT from two readings, why the intersection is used, why the temperature falls after the end point, and an improvement that really reduces heat loss.
The marking follows the conventions in published Cambridge mark schemes. The experiments, readings and wording on this page are our own.