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.