Performing a Titration
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Chemical Quantities and Calculations, Measurement and Units
Alternative titles: Acid–Base Titration Demonstration
Summary
A standard solution in a buret is added to an unknown solution in a flask until the reaction reaches its endpoint, signaled by an indicator color change (or pH jump). Initial and final buret readings are used to calculate the unknown molarity.
Procedure
- See instructions in the links below
Links
Setting up and Performing a Titration - Carolina Science:
📄 How to Perform a Titration - AACT: https://teachchemistry.org/classroom-resources/how-to-perform-a-titration
Variations
- Compare indicators (phenolphthalein vs. bromothymol blue) for strong acid–strong base titrations.
- Use a pH probe to create a titration curve and identify equivalence point without an indicator.
- Explore weak acid–strong base (or weak base–strong acid) titrations and note the shifted equivalence pH.
- Perform a back titration when the analyte reacts slowly or is insoluble.
Safety Precautions
- Wear splash goggles, lab coat/apron, and gloves at all times.
- When diluting, always add acid to water (never water to acid).
- Clamp the burette securely; keep the area dry and uncluttered to prevent slips and spills.
- If acid/base contacts skin, rinse immediately with water and notify the instructor.
- Neutralize and dispose of acidic/basic waste per local regulations; never return chemicals to stock bottles.
- Read burette volumes at eye level to avoid parallax; handle glassware carefully to prevent breakage.
Questions to Consider
- Why do we choose different indicators for different titrations? (Each indicator changes color over a specific pH range; you select one whose transition range spans the expected equivalence pH.)
- How is equivalence point different from endpoint? (Equivalence point is the stoichiometric point; endpoint is the observed signal - ideally they coincide but may differ slightly.)
- Why add titrant dropwise near the endpoint? (Small additions prevent overshooting, improving accuracy.)
- How does the balanced equation affect the calculation? (Polyprotic acids/bases require multiplying by the number of acidic hydrogens or hydroxides in the stoichiometry.)