Narration : 3. Preparation of a Standard Solution with a Volumetric Flask
- A volumetric flask is used to prepare a solution of definite concentration.
- First, add an appropriate amount of distilled water to the beaker containing the solid sample precisely weighed.
- Dissolve the sample completely using a stirring stick.
- And, transfer the entire liquid from the beaker into the flask.
- In order to transfer the entire solution in the beaker as well as on the stirring stick, wash them well with distilled water.
- Next, transfer the rinsed liquid to the flask.
- Repeat this operation once again.
- When two different liquids are mixed, a volume change may occur, therefore, don't add distilled water at once up to the marked line.
- While adding distilled water in small quantities a little below the marked line, gently shake the flask to homogenize the solution.
- First, move your eyes to the level of the marked line of the flask.
- Then, add distilled water drop by drop with a transfer pipette till the base of meniscus matches with the marked line.
- Seal the stopper firmly by pressing it. By inverting and turning the flask about ten times, mix the solution well.
- It should be noted that shaking the flask sideways in this manner does not mix the solution well.