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Guide: After the volumetric flask is purchased, it must be cleaned and calibrated; so that it will be used only after the calibration is qualified...
1. After the volumetric flask is purchased, it must be cleaned and calibrated to be used only after the calibration is qualified.
2. Substances that are easy to dissolve and do not generate heat is going to be directly transferred to the volumetric flask for dissolution. Other substances aren't dissolved availably in the volumetric flask. The solute should be dissolved in the beaker and then transferred to the volumetric flask.
3. Attention should be paid to the solution that will exothermic, endothermic or change in volume after mixing water and organic solvents (such as methanol, etc.): for those with heat; add an appropriate amount of solvent (about 0.5 cm from the bottle marking line). letting it cool until reconstitute the volume to the mark at room temperature. If the volume changes, add an appropriate amount of solvent (do not add it to the narrow neck to facilitate shaking); shake it, then add it to about 0.5 cm away from the marking line of the bottle, leave it for a period of time and then adjust the volume to the scale.
4. The total amount of solvent used for washing the beaker can't exceed the marking line of the volumetric flask.
5. The volumetric flask can't be heated. If the solute is exothermic during dissolution, wait for the solution to cool before transferring; since typical volumetric flasks are calibrated at 20°C. If a solution with a higher or lower temperature is injected into the volumetric flask, the volumetric flask will expand and contract with heat. At last, the measured volume will be inaccurate and resulting in an inaccurate solution concentration.
6. The volumetric flask can only be used to prepare the solution that cannot be stored for a long time. Because the solution may corrode the bottle body (especially the alkaline solution), which will affect the accuracy of the volumetric flask.
7. The volumetric flask should be washed in time after use.
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