Empirical formula calculations: using moles
I can determine the empirical formulae of simple compounds using reactant masses or percentage composition.
Empirical formula calculations: using moles
I can determine the empirical formulae of simple compounds using reactant masses or percentage composition.
Lesson details
Key learning points
- Empirical formula is the simplest whole number ratio of atoms of each element in a compound.
- Using the masses of elements reacted together, or their percentage compositions, calculate the empirical formula.
- Knowing the relative formula mass of a substance, and its empirical formula, calculate the molecular formula.
- Know that we are using moles, and molar ratios to calculate formulae
Common misconception
Pupils easily confuse empirical and molecular formula.
Provide multiple examples of formula and challenge pupils to distinguish them as molecular or empirical formula; if the former, push pupils to suggest the molecule's empirical formula.
Keywords
Empirical formula - A substance's empirical formula shows the simplest whole number ratio of atoms of each element in a compound.
Relative formula mass - The relative formula mass of a substance is the sum of the relative atomic masses of all the atoms in a formula.
Molecular formula - A substance's molecular formula shows the actual number of atoms of each element in a molecule of a compound.
Mole - A mole of something is 6.02 × 10²³ of it. The mass of a mole of a substance is its relative mass expressed in grams.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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