Titrations and yield extra: GCSE Chemistry
Titration method, concentration calculations, percentage yield, atom economy and related required practical
The short version
Use burette and pipette, calculate concentration from titre, then percentage yield and atom economy for industrial processes.
Key idea
Phenolphthalein: pink in alkali, colourless in acid. Methyl orange: yellow in alkali, red in acid
Grade 2–3: Add one liquid drop by drop until the colour flips. That tells you when they have cancelled out.
Grade 5–6: I can name pipette, burette, flask, indicator and white tile.
Grade 9: I state that the known moles come from concentration × volume, then the equation ratio gives the unknown. Universal indicator is too gradual for a precise end point.
Go a bit deeper
Write the method in this order — examiners buy the sequence
Grade 2–3: Keep adding until the colour flips, write the number, and do it again until the numbers almost match.
Grade 5–6: I can list pipette 25.0 cm^3, burette, flask, white tile, and concordant within 0.10 cm^3.
Grade 9: I rinse with the correct solution, go dropwise at the end, and I can justify discarding a non-concordant titre. I never rinse the flask with alkali - leftover alkali would need extra acid.
Worked example
Worked example
Grade 2–3: Add one liquid drop by drop until the colour flips. That tells you when they have cancelled out. Grade 5–6: I can name pipette, burette, flask, indicator and white tile. Grade 9: I state that the known moles come from concentration × volume, then the equation ratio gives the unknown. Universal indicator is too gradual for a precise end point.
Lessons in this topic
- What a titration is
- Required practical: titration
- Concentration calculations
- Percentage yield
- Atom economy
- Putting yield and titration together
In the app each lesson is video (when we have a real YouTube id) then intro, learn and summary steps.
What the examiner wants
Describe titration steps, calculate moles and concentration, and compute % yield and atom economy including limiting reactant ideas.
Try these questions
Cover the answers and have a go first. Worked solutions are underneath.
The titre is
A 25.0 cm³ portion of alkali is measured with a
Concordant titres agree within about
The conical flask should be rinsed with
Common mistakes
- Universal indicator is not the school titration indicator. Phenolphthalein or methyl orange give a sharp change. Do not swap pipette (fixed volume) with burette (variable volume).
- Do not rinse the conical flask with alkali. Leftover alkali would increase the titre. Concordant means within 0.10 cm^3, not "quite close".
- Leaving volume as 25 instead of 0.025 makes the answer 1000 times too small. Convert cm^3 to dm^3 before you multiply or divide.
- Do not invert the formula (theoretical / actual). Yield over 100% usually means wet or impure product, or a wrong theoretical mass - not a bonus from nowhere.
Answers and working
Frequently asked questions
Is GCSE Titrations and yield extra on Combined Science and Triple?
Titrations and yield extra is Triple-only Chemistry. Combined Science students can skip it.
Which exam board is this Titrations and yield extra page for?
The ideas are board-agnostic for AQA, Edexcel, OCR, WJEC and CCEA. Paper lengths and question numbers differ — check your specification.
Is Titrations and yield extra Foundation or Higher?
The core ideas appear on both tiers. Higher papers add extra application and some HT-only detail, marked in lessons with a Higher badge.
Learn, try, get feedback, fix the mistake
Open the stepped lesson, then the quiz with hints. Required-practical and calculation questions use the same method you will need in the paper.
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