Moles of the known
Convert the known solution's volume and concentration to moles.
AQA 8462 · Titration concentration
Titration: the mole ratio is not always 1:1
The mole-ratio mark. The balanced equation determines the conversion between the two substances, and the mark sits on that conversion rather than on the concentration arithmetic.
Reviewed family · Studara-authored items · No grade-uplift claim
The lost mark
One answer. Several places the method can fail.
Studara does not reduce the response to right or wrong. The reviewed contract checks these states independently.
Apply the ratio
Use the balanced equation's ratio to convert to moles of the unknown.
Concentration
Divide by the unknown's volume in dm³ and give the concentration.
Why it goes wrong
The diagnosis stays uncertainty-safe.
A wrong response can support a specific measured diagnosis. A blind multiple-choice diagnostic records only a possible cause until later working provides stronger evidence.
01
The error
Carrying the moles straight across from one solution to the other, without applying the ratio from the balanced equation.
02
Why it survives revision
For HCl + NaOH the ratio IS 1:1, and that is the reaction the technique is taught on. Every step of the calculation is correct and the shortcut is invisible until the acid changes.
The worked repair
Repair the smallest broken step.
Teaching is not evidence. This one move is the repair; the proof checks begin after it disappears.
Write the balanced equation and read its ratio out loud before converting moles from one substance to the other.
What happens after the repair
Correction is the start, not the result.
Immediate
Asked again straight away, on a different question
The repair leaves the screen and a new authored item checks the method unassisted. Being taught something is never evidence that it was learned, so this is the first stage that counts at all.
Delayed
Asked again after at least 1 day
A parallel form of the same method, unassisted, with the repair no longer on screen. A retest in the same session does not count.
Transfer
Asked again when the surface changes
The transfer form uses a diprotic acid such as H₂SO₄, where the ratio is 1:2 and the shortcut and the method give different answers.
Exam
Asked again under exam conditions
Timed, carrying the mark tariff, in an exam-like response format and aligned to the specification. Any one of those missing and the evidence is refused.
REVIEWED BOUNDARY
This page covers one reviewed family: Titration concentration. Convert volumes, preserve the balanced-equation mole ratio, and expose all five calculation-mark states. Other families within the same GCSE Chemistry topic are outside this reviewed journey, and Studara does not apply the proof label to material that has not been reviewed. No grade-uplift claim is made anywhere on this site.
Straight answers
Before you use this guide.
Do I always carry moles straight across in a titration?
Only when the balanced equation is 1:1, as it is for HCl and NaOH. For a diprotic acid such as H₂SO₄ the ratio is 1:2 and carrying moles across gives an answer that is out by a factor of two.
How do I convert cm³ to dm³?
Divide by 1000. Concentration in mol/dm³ needs the volume in dm³, and this conversion is a separate place marks are lost.
Does Studara guarantee a higher grade?
No. Studara has not run a controlled outcome study and publishes no grade-uplift claim. What has been measured, what is withheld, and the metric that failed its bar are all on the public evidence page.
Turn this method into evidence