#2.1.3a
explanation and use of the terms:
(i) amount of substance
(ii) mole (symbol ‘mol’), as the unit for amount of substance
(iii) the Avogadro constant, NA (the number of particles per mole, 6.02 × 1023 mol–1)
(iv) molar mass (mass per mole, units g mol–1),
(v) molar gas volume (gas volume per mole, units dm3 mol–1)
Amount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2.
The value for NA and the molar gas volume at RTP are provided on the Data Sheet.
#2.1.3b
use of the terms:
(i) empirical formula (the simplest whole number ratio of atoms of each element present in a compound)
(ii) molecular formula (the number and type of atoms of each element in a molecule)
Definitions not required.
#2.1.3c
calculations of empirical and molecular formulae, from composition by mass or percentage compositions by mass and relative molecular mass
To include calculating empirical formulae from elemental analysis data (see also 6.3.2e).
#2.1.3d
the terms anhydrous, hydrated and water of crystallisation and calculation of the formula of a hydrated salt from given percentage composition, mass composition or based on experimental results
PAG1
#2.1.3e
calculations, using amount of substance in mol, involving:
(i) mass
(ii) gas volume
(iii) solution volume and concentration
Learners will be expected to express concentration in mol dm–3 and g dm–3.
#2.1.3f
the ideal gas equation:
\(pV = nRT\)
The value for R is provided on the Data Sheet. Learners will be expected to express quantities in SI units.
#2.1.3g
use of stoichiometric relationships in calculations
#2.1.3h
calculations to determine:
(i) the percentage yield of a reaction or related quantities
(ii) the atom economy of a reaction
#2.1.3i
the techniques and procedures required during experiments requiring the measurement of mass, volumes of solutions and gas volumes
PAG1
#2.1.3j
the benefits for sustainability of developing chemical processes with a high atom economy.