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0.03
Divide by 1000.
O Level · English Medium · Cambridge · Chemistry
Quantities and chemical calculations
Use a titration equation to calculate an unknown concentration.
Original Kidemy further-topic investigation. This optional lesson is shared by related upper pathways; select suitable depth with a teacher. It does not certify complete grade or board coverage.
Learn the idea
A titre is the delivered volume used in the calculation. Convert it to dm³ when concentration is mol/dm³. The stoichiometric ratio comes from a balanced equation; equal volumes do not imply equal concentrations for every reaction.
Worked example
H2SO4+2NaOH→Na2SO4+2H2O. A 25.0cm³ acid sample reacts with 20.0cm³ of 0.100 mol/dm³ NaOH. Base amount0.00200 mol, acid0.00100 mol, so acid concentration0.0400 mol/dm³.
- Balance the equation.
- Convert volume and use mole ratio.
- Check units and measurement limits.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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0.008
n=cV.
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2
The coefficient ratio is 1:2.
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Base0.003 mol; acid0.0015 mol; concentration0.0015/0.025=0.06 mol/dm³.
Use the2:1 ratio and volume conversion.
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Show model answer and explanation
An overshoot is a procedural error and should be recorded and handled by a stated rule.
Explain consistency and transparent exclusions.
Apply the idea
Solve a fictional titration on paper and explain the ratio and precision.
Review with a guardian or teacher
- Use the stated evidence or givens.
- Show reasoning rather than only a result.
- Review and explain one correction.
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