Library / Foundations: Chemistry / FCH-06
Foundations: Chemistry
Concentration of a solution
Moles of solute per cubic decimetre of solution.
- Ref
- FCH-06
- Rev
- v1
- Field
- Foundations: Chemistry
- Result
- c [mol/dm³]
c in mol/dm³, n in mol, V in dm³ (divide cm³ by 1000). The mass concentration is m / V in g/dm³.
Concentration says how much dissolved chemical there is in each litre of solution.
Calculator
mol/dm³
g
g/mol
cm³
- Mass concentration16 g/dm³
- Moles of solute0.1 mol
What drives the result
Each variable is moved across its typical range while the others stay at the values above. The longest bar is the key driver.
Concentration (mol/dm³) current value 0.4 mol/dm³
mMass of soluteKey driver
0.00150
MrRelative formula mass
0.03216
VVolume of solution
0.0210
- 4.0 g of NaOH in 250 cm³ gives 0.40 mol/dm³ (16 g/dm³).
- Doubling the volume of water for the same solute halves the concentration.
Chart data as tables
Ranked variables
| Variable | Typical range | Lowest result | Highest result | Swing (mol/dm³) | Local step | Change in result |
|---|---|---|---|---|---|---|
| m Mass of solute | 0.01 to 500 g | 0.001 | 50 | 50 | +10% | +10 % |
| Mr Relative formula mass | 1 to 500 g/mol | 0.032 | 16 | 15.97 | +10% | −9.09 % |
| V Volume of solution | 10 to 5,000 cm³ | 0.02 | 10 | 9.98 | +10% | −9.09 % |
Sweep of Volume of solution
| Volume of solution (cm³) | Concentration (mol/dm³) |
|---|---|
| 10 | 10 |
| 21.75 | 4.599 |
| 47.29 | 2.115 |
| 102.8 | 0.9725 |
| 223.6 | 0.4472 |
| 486.2 | 0.2057 |
| 1,057 | 0.09457 |
| 2,299 | 0.04349 |
| 5,000 | 0.02 |
Sweep one variable
Concentration (mol/dm³)Hover, touch, or use the arrow keys on the chart
Variables and how each one contributes
c
Concentration
What the equation gives you. Everything else feeds it.
m
Mass of solute
Mass dissolved. Directly proportional.
Mr
Relative formula mass
Molar mass of the solute (NaOH = 40). Inversely proportional.
V
Volume of solution
Final volume of the solution. Inversely proportional.
Worked example with the values above
- Moles: n = 4 / 40 = 0.1 mol.
- Volume in dm³: 250 / 1000 = 0.25.
- c = 0.1 / 0.25 = 0.4 mol/dm³.
Assumptions and limits
- Solute fully dissolved.
- V is the total solution volume, not the water added.
Common mistakes
- Leaving the volume in cm³.
- Confusing g/dm³ with mol/dm³.
Statistics and uncertainty
A volumetric flask is accurate to about ±0.1 cm³ on 250 cm³ (0.04%), so the mass measurement usually dominates the uncertainty.
Where it is used
- Preparing standard solutions.
- Dosing and process reagent control.
Maths you need
- Moles: n = m / Mr
- Unit conversion: cm³ to dm³