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Converting units explained

Syllabus VWO: Mathematical skills

Choose compatible units, convert them and check whether a result makes sense.

Line up your quantities

Write what each number represents and its unit. For c = n / V in mol/L, V must be in litres. Divide a volume in mL by 1000 to obtain litres.

Check the scale

250 mL is less than one litre. A conversion to 250 L cannot be right. Take care with cubic units: 1 m³ = 1000 L = 1 000 000 cm³.

Worked example

250.0 mL of solution contains 0.0500 mol of solute. Calculate c in mol/L.

  1. V = 250.0 / 1000 = 0.2500 L.
  2. c = n / V = 0.0500 / 0.2500.

c = 0.200 mol/L.