M.2—Unit conversions, standard form, logs and algebra

Convert every quantity to the units required by the equation before calculating. Common traps include cm³↔dm³, kPa↔Pa, °C↔K, mg↔g and J↔kJ.

Use standard form for very large or small values, rearrange the formula symbolically, then substitute numbers with units. For pH, logarithms reverse powers of ten: [H⁺] = 10⁻pH.

250 cm³ = 0.250 dm³; 27 °C = 300 K approximately. A pressure of 101 kPa is 101 000 Pa.

Do not convert temperature by adding 273 to a temperature difference, and do not mix cm³ with dm³ in n = cV.