Standard Solution

Standard Solution

6.6

Standard Solution

Definition of standard solution

Solution with known concentration

Preparation of standard solution from a solid

	Procedure
1.	Determine the mass of solid needed.	\(n=\dfrac{MV}{1000}\)
2.	Add some distilled water to the solid measured.
3.	Stir the mixture with a glass rod until all of the solid dissolves in the solution.
4.	Transfer the solution into a volumetric flask using a filter funnel.
5.	Rinse the filter funnel with a little bit of distilled water.
6.	Add distilled water until the meniscus of the water nearing the calibration mark.
7.	Use a dropper to add distilled water slowly until the meniscus of the water is aligned exactly at the calibration mark.
8.	Close the volumetric flask using a stopper and shake the flask until the solution is mixed evenly.

Preparation of standard solution using the dilution of solution

During dilution, the added water will change the concentration of the solution but not change the number of moles of solute present in the solution.

Formula

\(\begin{aligned} \,\\ n_1&=n_2\\ \,\\ \dfrac{M_1V_1}{1000}&=\dfrac{M_2V_2}{1000}\\ \,\\ M_1V_1&=M_2V_2\\ \,\\ \end{aligned}\)

\(M_1:\)		Molarity of aqueous solution (stock solution) before dilution
\(V_1:\)		Volume of aqueous solution (stock solution) before dilution
\(M_2:\)		Molarity of aqueous solution (prepared solution) after dilution
\(V_2:\)		Volume of aqueous solution (prepared solution) after dilution

	Procedure
1.	Determine the volume of stock solution needed.	\(M_1V_1=M_2V_2\)
2.	Take out the calculated, \(V_1\) solution using pipette.
3.	Transfer the solution \(V_1\) into a volumetric flask.
4.	Add distilled water until the meniscus of the water nearing the calibration mark.
5.	Use a dropper to add distilled water slowly until the meniscus of the water is aligned exactly at the calibration mark.
6.	Close the volumetric flask using a stopper and shake the flask until the solution is mixed evenly.