Chapter summary
Chemical Calculations, at a glance
Write formulae and equations, then calculate moles, mass and molar mass.
SEC G2 Science K223 / K225 (2027)
Quick revision
Revisit the essentials, then return to an explanation when you need it.
- Formula
Write the correct formula, using ion charges for ionic compounds.
- Equation
Balance atoms with coefficients, never by changing subscripts, and add state symbols.
- Relative mass
Add the Ar values, counting every atom inside brackets.
- Moles
n = m / M, m = n x M or M = m / n, with mass in g and M in g mol-1.