- OCR
Titrations: calculating an unknown concentration
I can calculate the concentration of an acid using results from a neutralisation titration.
- OCR
Titrations: calculating an unknown concentration
I can calculate the concentration of an acid using results from a neutralisation titration.
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Lesson details
Key learning points
- Data collected during a titration allows chemists to determine a solution’s unknown concentration.
- Concordant titres should be used when calculating a mean volume used to neutralise a solution.
- The coefficients in a balanced equation indicates the stoichiometry (i.e. molar ratio) between substances in a reaction.
- The concentration of an unknown solution is found using the relationship: concentration = moles ÷ volume (in dm³).
Keywords
Titration - A technique in volumetric analysis that is used to find the exact volumes of solutions that react with each other.
Titre - The volume of titrant needed to reach the end point in a titration.
Concordant - Readings within a certain range. For titrations, these usually need to be within 0.10 cm³ of each other.
Coefficient - The number placed in front of a chemical formula to balance an equation; it shows the ratio of substances in a reaction.
Mole - 1 mole contains 6.02 × 10²³ particles. The mass of a mole of a substance is its relative mass expressed in grams.
Common misconception
Pupils use all of their titration results to calculate an average volume used during titration. Pupils also tend to miss steps in this multi-step process.
Stress the need to use concordant results when calculating an average volume for neutralising a solution via titration. Use a calculation grid to help keep each calculation step clearly organised.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is a mole?
Q2.How do you calculate the number of moles from mass?
Q3.Calculate the number of moles in 50 g of NaCl (relative formula mass of NaCl = 58.5).
Q4.How do you calculate concentration in mol/dm³?
Q5.How do you convert cm³ to dm³?
Q6.Convert 250 cm³ to dm³.
Assessment exit quiz
6 Questions
Q1.Match the following key words to their definition.
A technique to find exact volumes of reacting solutions.
The volume of titrant needed to reach the end point.
Readings within ±0.10 cm³ of each other.
A number showing the ratio of substances in a reaction.
1 mole contains 6.02 × 10²³ particles.