Titration is a fundamental quantitative analytical technique used in chemistry to determine the concentration of an unknown solution. The process involves carefully adding a solution of known concentration, called the titrant, to a solution of unknown concentration, called the analyte. The key to titration is precise volume measurement and identifying the equivalence point where the reaction is complete.
Successful titration requires specific laboratory equipment, each serving a crucial purpose. The burette provides precise volume delivery of the titrant with graduations for accurate measurement. The conical flask holds the analyte solution and allows for easy swirling during the titration. A pipette ensures accurate volume measurement of the analyte. Indicator solutions signal the endpoint through color changes. The stand and clamp system provides stable support. Precision and accuracy in measurements are absolutely essential for reliable titration results.
The titration process follows a systematic procedure. First, prepare the analyte solution in a conical flask. Fill the burette with the titrant solution of known concentration. Add a few drops of indicator to the analyte, which will signal the endpoint through a color change. Slowly add the titrant while continuously swirling the flask to ensure proper mixing. As you approach the endpoint, add the titrant drop by drop to avoid overshooting. Observe the color change carefully and record the exact volume of titrant used when the endpoint is reached.
Let's work through a practical acid-base titration example. We're titrating hydrochloric acid with sodium hydroxide. The balanced chemical equation shows a one-to-one molar ratio. Given that 25.0 milliliters of 0.1 molar sodium hydroxide neutralizes 20.0 milliliters of hydrochloric acid, we can calculate the concentration using the formula M1V1 equals M2V2. Substituting our values: the molarity of HCl times 20.0 equals 0.1 times 25.0, giving us 0.125 molar for the HCl concentration. The endpoint is indicated by a color change from clear to pink with phenolphthalein indicator.
Titration curves provide valuable analytical information by plotting pH versus volume of titrant added. The characteristic S-shaped curve shows several key features: the initial pH reflects the starting solution, a buffer region where pH changes gradually, the equivalence point marked by the steepest slope, and the endpoint where the indicator changes color. Strong acid-strong base titrations show a sharp equivalence point, while weak acid-strong base titrations display a more gradual buffer region. Understanding these curves helps chemists choose appropriate indicators and interpret titration results accurately.