Chemistry: Volumetric Analysis

Volumetric analysis is a quantitative laboratory method used in chemistry to determine the concentration of a solution (the analyte) by a reaction with a solution of known concentration (the titrant).
This technique involves the use of titration where the volume of titrant that reacted with the analyte is noted.
The point of equivalence or the end point is indicated by the colour change of an appropriate indicator.

Volumetric Analysis Workflow

Step 1: Preparation: Before starting a volumetric analysis, you must ensure that all apparatus, such as the burette and pipette, are clean and calibrated.
Step 2: Fill the Burette: Fill the burette with the titrant solution, ensuring it is filled above the zero mark, and then adjust to the zero.
Step 3: Pipetting the Sample: Use the pipette to transfer a precise volume of the analyte into the conical flask. Add a few drops of indicator.
Step 4: Titration: Gradually add the titrant from the burette to the analyte in the conical flask, swirling to ensure mixing. Observe for the colour change.
Step 5: Endpoint Determination: The end point or equivalence point is reached when the color change persists, indicating that all analyte has reacted with the titrant.
Step 6: Record Observations: Record the final reading of the burette and subtract initial reading to get the volume of titrant used. Repeat the titration several times to get an accurate average measurement.

Accuracy: Precise using of burette, pipette and other apparatus is crucial as even a small variation in volume can influence the result.
Indicator selection: The choice of an indicator becomes crucial as it should change colour at the equivalence point.
Reagent concentration: The concentration of the titrant should be known accurately, as this is used to calculate the concentration of the analyte.

As you are often working with corrosive or harmful solutions, eye protection and gloves should be worn during the setup and the experiment.
Any spills should be immediately cleaned and the workbench should be kept clear of unnecessary items to prevent accidents.

Parallax Error: If the meniscus level is not read at eye level, a parallax error can occur, skewing results.
Hydration Error: Not maintaining solution temperature can lead to hydration error, as some solutions are temperature dependent.
Unreacted solutions or slight color changes can lead to a false end point determination. Multiple titrations and averaging the results can help mitigate some of these errors.