Titration Table O Level: Setup & Use

A titration table for O Level chemistry records the burette readings and volumes of titrant used during a titration experiment, allowing you to calculate the average titre and determine the concentration of an unknown solution. You enter your initial and final burette readings for each trial, and the table (or your own calculations) gives you the volume added, which you then use to find the mean titre. This article explains how to structure that table, avoid common errors, and use the results correctly in your practical exam.

Formula

The titre (volume of titrant delivered from the burette) is simply the difference between the final and initial burette readings:

Volume added (cm³) = Final reading (cm³) – Initial reading (cm³)

Where:

• Initial reading – the volume of liquid in the burette before you start the titration (in cm³).
• Final reading – the volume of liquid in the burette after the endpoint is reached (in cm³).
• Volume added (titre) – the amount of titrant used, in cm³.

In a full titration table, you repeat this for several trials (usually 2–4) and then calculate the mean titre using only the concordant (closely agreeing) results.

Worked Example

Using the default values from the calculator above (initial = 0.00 cm³, final = 25.00 cm³):

1. Write down the initial burette reading: 0.00 cm³.
2. Write down the final burette reading: 25.00 cm³.
3. Subtract the initial from the final: 25.00 – 0.00 = 25.00 cm³.

The titre is 25.00 cm³. In a real experiment, you would repeat this and then average the concordant titres.

How to Build a Titration Table

O Level chemistry practical exams (such as those from Cambridge or other boards) expect a specific layout for the titration table. A typical table has columns for:

• Trial number (rough, 1, 2, 3)
• Final burette reading (cm³)
• Initial burette reading (cm³)
• Volume of titrant used (cm³) – calculated by subtraction

You should record readings to the nearest 0.05 cm³ (the typical precision of a burette). The first trial is often a rough titration to get an approximate endpoint, and it is not used in the average.

How to Calculate the Average Titre

After you have all your titres, you must decide which ones are concordant – that is, within 0.10 cm³ of each other (or as specified by your exam board). Only concordant results are averaged. For example:

• Trial 1 (rough): 24.50 cm³
• Trial 2: 25.00 cm³
• Trial 3: 25.10 cm³
• Trial 4: 25.05 cm³

Trials 2, 3, and 4 are concordant (range = 0.10 cm³). The average titre = (25.00 + 25.10 + 25.05) / 3 = 25.05 cm³. You would use this average in your stoichiometric calculation.

Common Mistakes and How to Avoid Them

Students often lose marks on the titration table for avoidable errors:

• Forgetting to subtract – always calculate the volume used, not just the final reading.
• Using the rough titre in the average – the rough trial is only for orientation; exclude it.
• Averaging non-concordant results – if one titre is far off (e.g., 24.80 vs 25.00), repeat the titration.
• Reading the burette incorrectly – read at eye level, from the bottom of the meniscus.
• Recording readings with wrong precision – always give two decimal places (e.g., 25.00, not 25).
• Not cleaning the burette properly – rinse with the titrant, not water, before filling.

Using the Titre in Calculations

The average titre is used in the mole calculation to find the unknown concentration. For a reaction like HCl + NaOH → NaCl + H₂O, the steps are:

1. Write the balanced equation and note the mole ratio (1:1 here).
2. Calculate moles of known solution: moles = concentration (mol/dm³) × volume (dm³).
3. Use the mole ratio to find moles of unknown.
4. Calculate concentration of unknown: concentration = moles / volume (dm³).

Remember to convert cm³ to dm³ by dividing by 1000.

Frequently Asked Questions

Why do we do a rough titration first? The rough titration gives a quick estimate of the endpoint, so you can add the titrant faster and then slow down near the expected endpoint in the accurate trials. It also helps you avoid overshooting in the precise runs.

How many decimal places should I record? Burettes typically measure to 0.05 cm³, so record readings to two decimal places, e.g., 25.00 cm³ or 25.05 cm³. Never record one decimal place (25.0) – that implies a precision you don’t have.

What does ‘concordant’ mean in titration? Concordant titres are those that agree within 0.10 cm³ of each other (some boards allow 0.20 cm³). Only concordant results are averaged to reduce error.

Can I use the calculator for my actual exam? No – calculators are not allowed in the practical exam for the titration table itself, but you can use a calculator for the mole calculations. This tool is for practice and checking your work.

What if my titres are not concordant? If the titres differ by more than 0.10 cm³, you should repeat the titration. In an exam, you may have time for one more trial; if not, average the closest two and note the anomaly.

Why is the average titre not a whole number? Because the endpoint is determined by a colour change, which is not exact. The volume added varies slightly, so the average is a decimal. That’s normal.

Related

• COD Modern Warfare 4: Unlock All Operators
• Space-Grade Parts vs COTS: When Is Commercial Enough?
• Use Siri to Start Workout: Quick Guide

in initial | Initial burette reading | cm³ | 0.00 | 0
in final | Final burette reading | cm³ | 25.00 | 0
out titre | Volume added (titre) | cm³ | final - initial | 2