Thermometric titration sim

What the sim shows

25.0 cm³ of hydrochloric acid of unknown concentration is pipetted into a polystyrene cup standing in a beaker. The burette holds 1.00 mol/dm³ sodium hydroxide, and both solutions start at 20.0 °C. All the liquids are colourless throughout, so the thermometer is the only way to follow the reaction (ethanoic acid smells faintly of vinegar). Add the alkali one portion at a time, stir until the reading stops rising, and record the highest temperature. Neutralisation gives out heat, so the temperature climbs while acid is left. After the end point no more heat is made, and each portion of alkali at 20 °C, together with heat lost to the room, cools the mixture. Use 5.0 cm³ portions up to 20 cm³, 2.0 cm³ portions to 30 cm³, then 5.0 cm³ again. The early points bend over because each portion adds more liquid to warm (with 5.0 cm³ portions all the way, the lines meet early, at about 21.6 cm³), so line each ruler up with the points nearest the peak. Where the lines meet is the end point, and its height above 20.0 °C is the maximum rise. Concentration of acid = 1.00 × end-point volume ÷ 25.0. The lid keeps more heat in, so the rise is bigger. Ethanoic acid, a weak acid, gives a rise only slightly smaller, because its enthalpy of neutralisation is only slightly smaller. Source: −57.1 kJ/mol (strong acid with strong alkali) and −56.1 kJ/mol (ethanoic acid) are typical school data-book values; published values differ by about 1 kJ/mol. Model limits: solution density 1.00 g/cm³ and c = 4.18 J/(g °C); the heat taken up by the cup and thermometer is ignored; heat loss is a fixed share of the warmth above the room at each reading (1% with the lid, 3% without); readings are scattered by up to ±0.2 °C; and the waiting time passes only while you stir. Wear eye protection: 1.00 mol/dm³ sodium hydroxide is corrosive. Singapore O-Level 6092 does not name this method; use it there for practical data handling.

• Thermometer: its red spirit column is the only sign of the reaction (magnified on the right)
• Polystyrene cup and lid, in a 250 cm³ beaker for support
• Graph: drag the two rulers by their square handles; where they cross is the end point. Grey open circles: the earlier run

Use it in your lessons

• Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
• Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
• Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.

Free guide: 12 practicals as sims, and how to run one in a lesson →

Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.