Chemistry study notes
Chemical Calculations
Turn formulae, measurements and equations into defensible numerical answers.
O-Level 6092 (2026) / SEC G3 K324 (2027)
Choose a topic
6 topicsRead and construct formulae
Subscripts count atoms; ion charges determine ratios.
Balance atoms, then account for ions
A reaction changes arrangement, not the total number of atoms.
The mole is a counting unit
Connect microscopic particles to measurable mass.
Use the equation ratio
Convert to moles before comparing reactants.
Concentration and titration
Volume tells you moles only when concentration is known.
Composition, formulae, yield and purity
Distinguish the composition of a compound from the success of a preparation.
Pure only
Scope and references
Learning outcomes and sources
4. Chemical Calculations (6092 / K324). Use the outcome map to find the explanation for a particular syllabus requirement.
See the learning outcome map
4.1(a) Use chemical symbols and formulae
- Element symbols
- Formulae of named syllabus compounds
4.1(b) Translate atom counts and formulae
- Subscripts, brackets and coefficients
- Reverse interpretation
4.1(c) Balance ion charges to obtain formulae
- Simple and polyatomic ions
- Deduce ion charge from formula
4.1(d) Interpret equations and states
- s, l, g and aq
- Coefficients as mole ratios
4.1(e) Construct balanced equations
- Full equations with states
- Ionic equations and spectators
- Conserve atoms and charge
4.2(a) Define relative atomic mass
- Carbon-12 comparison
- Average atomic mass
4.2(b) Define and calculate relative molecular/formula mass
- Sum relative atomic masses
- Molecular versus ionic terminology
4.2(c) Define the mole using the Avogadro constant
- Specified entities
- Mass-mole-particle relationships
4.2(d) Calculate elemental mass percentages
- Element contribution divided by formula mass
4.2(e) Deduce empirical and molecular formulae
- Mass-to-mole ratios
- Molecular mass multiplier
4.2(f) Calculate reacting masses and gas volumes
- Balanced mole ratios
- 24 dm3 per mol at room temperature and pressure
- Limiting reactants
- No variable-temperature gas laws
4.2(g) Use solution concentration
- mol/dm3 and g/dm3
- Titration data
- Unfamiliar reactions with supplied information
4.2(h) Calculate yield and purity
- Actual versus theoretical yield
- Pure substance versus total sample mass
- 2026 Pure Chemistry 6092
Official topic 4, pages 14-15. Original explanations mapped to the stated outcomes; 2026 and 2027 topic content agrees.
- 2027 Pure Chemistry K324
Official topic 4, pages 14-15. Original explanations mapped to the stated outcomes; 2026 and 2027 topic content agrees.
- 2026 Combined Chemistry 5086 / 5088
Official topic 4, pages 30. Original explanations mapped to the stated outcomes; 2026 and 2027 topic content agrees.
- 2027 Combined Chemistry K326 / K328
Official topic 4, pages 30. Original explanations mapped to the stated outcomes; 2026 and 2027 topic content agrees.
- Grail: 6092 Chemistry Complete Notes, Version 1
Background consultation: Chapters 6-7, formulae and mole calculations, pp. 31-37. Teaching additions and examples are original; syllabus scope and chemistry independently checked.