Free titration timer for chemistry lab procedures. Time reagent addition rates, endpoint stabilisation, and between-run intervals. Precise countdown for accurate results.
Near the equivalence point, slow reagent addition with mixing time between drops is critical to avoid overshooting the endpoint. Timing the swirl-and-observe interval (typically 10–30 seconds per drop near endpoint) standardises the procedure and reduces operator error in endpoint identification.
For a persistent colour change endpoint (e.g. phenolphthalein in acid-base titration): consider the endpoint reached when the colour persists for 30 seconds after mixing. For potentiometric endpoints: wait for the reading to stabilise (typically 10–60 seconds) before recording the volume.
Allow 2–5 minutes between repeat titrations to rinse and refill the burette, prepare a fresh analyte sample, and allow the burette tip and stopcock to equilibrate. Record all concordant results (within 0.1 mL of each other). Three concordant results are typically required for accepted data.
Temperature: warm solutions react faster; cold slows reaction kinetics. Indicator response time: some indicators (methyl orange) change colour more slowly than others near the endpoint. Mixing efficiency: poor swirling extends the time needed for equilibration. Automated titrators eliminate operator timing variability.
Bulk phase (far from endpoint): 1–3 mL per second. Approaching endpoint (within 5 mL): slow to drop-by-drop, 2–5 seconds between drops. At and past the endpoint: half-drop additions (touch and swirl) with 10–30 second observation intervals. This progressive slowing is standard analytical technique.