cm³ and dm³, mass units, significant figures, standard form, percentages and mole ratios.
What you will learn
- Convert cm³, dm³, g, kg and tonnes
- Round to significant figures
- Use a mole ratio from an equation
The conversions chemistry uses most
1 dm³ = 1000 cm³
1 kg = 1000 g, 1 tonne = 1000 kg
concentration (g/dm³) = mass (g) ÷ volume (dm³)
- 250 cm³ = 250 ÷ 1000 = 0.25 dm³
- 5.0 g in 250 cm³: 5.0 ÷ 0.25 = 20 g/dm³
Most wrong concentrations come from dividing by cm³ instead of dm³.
Going the other way, multiply: 0.40 dm³ = 0.40 × 1000 = 400 cm³. For small masses, 1 g = 1000 mg, so 750 mg = 0.75 g; for large ones, 2.5 tonnes = 2500 kg = 2 500 000 g = 2.5 × 10⁶ g.
The rest of this lesson and its 9 practice questions are locked.
In this lesson
- The conversions chemistry uses most
- Figures, powers and ratios
- Try it: cm³ and dm³
9 practice questions, marked as you go; about 20 minutes in all.
Key terms
Resolution
In this unit: Required practicals and maths skills
The skills behind every chemistry practical and calculation: units, uncertainty, titrations, graphs, the equations and planning.