The solute is the dissolved substance. The solvent dissolves it. The solution is the mixture.
Concentration (g/dm³) = mass of solute (g) ÷ volume of solution (dm³). Use the final solution volume, not just the starting water volume.
1000 cm³ = 1 dm³. Divide cm³ by 1000.
250 cm³ = 0.250 dm³; 500 cm³ = 0.500 dm³. A litre is 1 dm³ and 1 mL is 1 cm³.
10 g of solute in 500 cm³ of solution:
1. Volume = 500 ÷ 1000 = 0.500 dm³.
2. Concentration = 10 ÷ 0.500 = 20 g/dm³.
Mass = concentration × volume.
For 250 cm³ of a 20 g/dm³ solution:
Mass = 20 × 0.250 = 5.0 g.
If volume is unknown: volume = mass ÷ concentration.
Higher Tier extension. At the same solution volume, doubling solute mass doubles concentration. With the same solute mass, doubling solution volume halves concentration. Adding solvent dilutes a solution: solute mass stays the same but is spread through a larger volume. In the diagram, assume equal volumes and each dot represents equal solute mass.
Use solution volume in dm³. Concentration = mass ÷ volume; mass = concentration × volume.
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