Check the unit before calculating
| Quantity | Relationship | Common pitfall |
|---|---|---|
| Volume | 1 L = 1,000 mL = 1,000,000 µL | Use final solution volume. |
| Molar concentration | 1 M = 1,000 mM = 1,000,000 µM = 1,000,000,000 nM | µ means micro; n means nano. |
| Molar mass | Numerically, 1 kDa corresponds to 1,000 g/mol | 50 kDa is 50,000 g/mol, not 50 g/mol. |
| Mass concentration | 1 mg/mL = 1 g/L; 1 ng/mL = 0.000001 g/L | Mass concentration needs molar mass to become molarity. |
| Mass/volume percent | 1% w/v = 1 g per 100 mL final solution | It is different from % w/w. |
Practice problems
- Convert 10 ng/mL of a 50 kDa molecule to nM.
- Find the mass of NaCl for 100 mL at 100 mM, with molar mass 58.44 g/mol and 100% purity.
- Find the stock volume for 100 mL at 10 mM from 100 mM stock.
- List three tenfold dilutions starting at 1,000 µM.
Show answers and calculator links
- 0.2 nM — check the concentration conversion.
- 0.5844 g — check solution preparation.
- 10 mL stock, brought to 100 mL final volume — check dilution.
- 100, 10, and 1 µM — check the series.
Use this worksheet
Print this page from your browser or link directly to it from a lesson or lab notebook. Use the calculator pages to inspect formulas and assumptions. These are educational exercises, not experimental protocols.
Reference
OpenStax Chemistry 2e: concentration units. Unit relationships and practice examples were checked October 19, 2026.