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The 5 Titration Mistakes That Cost the Most Marks

Titration questions look straightforward — add some numbers, get an answer — which is exactly why they're a trap. Examiners know students rush these, and the mark schemes are built to catch specific, predictable errors. Here are the five that show up again and again.

1. Mixing up mol/dm³ and g/dm³

The formula moles = concentration × volume only works when concentration is in mol/dm³. If a question gives you concentration in g/dm³, you must convert it to mol/dm³ first (divide by molar mass) before touching the titration formula. Students who skip this step get an answer that's numerically "close" but wrong by a factor of the molar mass — and lose the method marks along with it.

2. Forgetting to convert cm³ to dm³

Volumes in titration are almost always measured in cm³ (from a burette or pipette), but the formula needs dm³. Divide by 1000. This sounds obvious written down, but under exam pressure it's one of the most common silent errors — the working looks right, the final number is off by exactly a factor of 1000, and it's easy to miss unless you sanity-check your answer.

3. Using the wrong mole ratio from the equation

Once you know moles of acid and moles of base, you still need the balanced equation to relate them correctly. For example, in H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O, one mole of acid reacts with two moles of base — not one. Skipping this ratio (or assuming it's always 1:1) is a very common and very costly mistake, especially with diprotic acids.

4. Ignoring significant figures and giving an unrealistic answer

If your data was given to 3 significant figures, your final answer should generally match that precision — not be reported to 6 decimal places just because your calculator displayed them. Examiners specifically look for answers reported to a sensible, consistent number of significant figures matching the given data.

5. Not checking whether the answer makes physical sense

A concentration that comes out negative, or a volume of 50,000 cm³ for a burette reading, should be an immediate red flag that a step went wrong. Before moving on, take two seconds to ask: does this number make sense for the situation? This single habit catches a surprising number of errors before you submit a final (wrong) answer.

The one habit that fixes most of these

Write out every unit at every step — not just at the end. If you write "cm³" next to a number and the formula needs "dm³," the mismatch becomes visually obvious before you've locked in a wrong answer. Most titration mistakes aren't really chemistry mistakes; they're careless unit mistakes hiding inside a chemistry question.

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