- Calculate the mass of solid which must be dissolved in the given volume.
For example, to prepare of $250\; ml$ of a $0.2$ molar solution of sodium chloride, we need
$n$ $=$ $[NaCl]\cdot V$ $=$ $0.2\cdot 0.25$ $=$ $0.05\; mol$, ie
$m$ $=$ $n\cdot M$ $=$ $0.5\cdot 58.44$ $ =$ $ 2.922\; g$ $NaCl$
- Weigh accurately that mass:
- Introduce in a volumetric flask:
- Rinse with distilled water into the volumetric flask:
- Introduce distilled water:
- Stir to dissolve the solid:
- Fill distilled water to the mark:
- Stopper the flask and stir:
- The standard solution (the molarity is known) is ready to use !
Pictures taken from: → Lycée Clemenceau de Reims