Standard solution: definition in chemistry
Standard solution: A solution whose concentration is known accurately, used as a reference to measure the concentration of another solution.
A standard solution is usually made by dissolving a precisely weighed amount of a pure, stable solid and diluting it to an exact volume in a volumetric flask. Substances suitable for this, called primary standards, must not absorb water or carbon dioxide from the air, which is why sodium hydroxide is not one. Standard solutions are added from a burette in titrations, and dilutions of them are used to calibrate measuring instruments.
Examples
- 0.100 M sodium carbonate made from the dried, weighed solid
- Potassium hydrogen phthalate solution used to check the concentration of sodium hydroxide
- Hydrochloric acid of known molarity used to titrate an unknown base
- A series of copper(II) sulfate solutions used to calibrate a colorimeter