A standard solution is a solution whose concentration is accurately known. It is used as a reference in chemical analysis, especially in titrations, to determine the concentration of another solution.
Key Points:
- Known Concentration: The exact amount of solute per unit volume of solution is precisely known.
- Purpose: Used to react with a solution of unknown concentration to find its strength.
- Preparation: Usually prepared using a primary standard (a highly pure, stable, and non-hygroscopic substance).
- Examples of Primary Standards: Sodium carbonate (Na₂CO₃), potassium hydrogen phthalate (KHP), silver nitrate (AgNO₃).
Example:
If you have a solution of NaOH of unknown concentration, you can titrate it against a standard solution of HCl (whose concentration is known) to determine the NaOH concentration.