Titration is one of the most important quantitative techniques in chemistry. It allows you to determine the concentration of an unknown solution by reacting it with a solution of known concentration. In IB Chemistry, titration appears in both the internal assessment and Paper 3, making it essential to understand the method clearly. This article explains what titration is, how it works, and how to perform one accurately.
What Is Titration?
Titration is a laboratory technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration (the titrant).
The titrant is added gradually to the analyte until the reaction reaches a point where the amounts are stoichiometrically equivalent—this is the equivalence point.
In acid–base titrations, indicators or pH meters are typically used to detect this point.
Equipment Used in a Titration
A standard titration requires:
- A burette (to deliver titrant)
- A pipette (to deliver a fixed volume of analyte)
- A pipette filler
- A conical flask
- A white tile (to see color change clearly)
- A funnel (for filling the burette)
- An indicator or pH probe
Each piece plays a role in ensuring precision and minimizing measurement error.
The Titration Process Step-by-Step
1. Prepare the Equipment
- Rinse the burette with distilled water, then with the titrant
- Rinse the pipette with the solution it will measure
- Ensure no air bubbles are in the burette tip
These steps reduce contamination and improve accuracy.
2. Fill the Burette with Titrant
- Use a funnel to add titrant carefully
- Remove the funnel before starting (to avoid drips)
- Record the initial burette reading to two decimal places
Consistency in reading the meniscus is essential for IB marking.
3. Measure the Analyte with a Pipette
- Use the pipette to transfer a fixed, accurate volume (e.g., 25.0 cm³)
- Release it into a clean conical flask
- Add a few drops of appropriate indicator
This ensures a precise starting amount of the unknown solution.
4. Add Titrant Slowly While Swirling
- Open the burette tap to allow titrant to drip in
- Swirl the flask continuously
- As the color approaches the endpoint, add titrant drop-by-drop
This prevents overshooting and ensures a sharp color change.
5. Identify the Endpoint
The endpoint is where the indicator changes color.
It is an experimental approximation of the equivalence point.
Examples:
- Phenolphthalein: colorless → pink
- Methyl orange: red → orange/yellow
Use a white tile to observe subtle changes more easily.
6. Record the Final Burette Reading
Calculate the titer:
Titer = Final reading − Initial reading
Accurate titrations require concordant results—typically within 0.10 cm³ of each other.
Using Titration Data
Once you have a titer, you can determine the concentration of the unknown:
- Use the balanced equation to identify mole ratios
- Calculate moles of titrant added
- Use mole ratio to find moles of analyte
- Calculate concentration using:
c = n / V
This method links titration to stoichiometry and concentration calculations.
Common Sources of Titration Error
- Overshooting the endpoint
- Not rinsing equipment with correct solutions
- Parallax error when reading the burette
- Using the wrong indicator
- Not swirling consistently
- Air bubbles in the burette jet
- Measuring volumes inaccurately
Identifying and minimizing these errors is important in IA lab work.
FAQs
Why is a pipette more accurate than a measuring cylinder?
A pipette delivers a fixed, precise volume with minimal uncertainty, whereas a measuring cylinder has larger graduation intervals and greater user variability.
Why do titrations need concordant results?
Multiple consistent results improve reliability and allow you to calculate an average that reflects experimental precision.
What determines the best indicator?
The indicator must change color at the pH of the equivalence point. Strong acid–strong base titrations require different indicators than weak acid–strong base titrations.
Conclusion
Titration is a precise method used to determine the concentration of an unknown solution by reacting it with a standard solution. By mastering the steps—preparation, measurement, titrant addition, endpoint detection, and data analysis—you can perform accurate titrations and handle IB Chemistry calculations with confidence. This technique is essential for laboratory work and exam success.
