Question

analytical balances that are accurate to 0.0002 g; volumetric flasks of 50, 100, 250 and 500 mL; and volumetric pipets of 1, 2, 5, 10 and 25 mL. Describe how to prepare a solution containing 1.00 ug/mL of Ag+ (FM 107.87) starting from pure AgNO3 (FM 169.88), using only the glassware listed and specifying the mass of the starting material to be at least 0.2 g to ensure sufficient precision. Weigh out g of the starting material to 0.0002 g and transfer it to a -mL volumetric flask. Dilute to the mark. Withdraw from the volumetric flask with a volumetric pipet and transfer to a -mL volumetric flask. Dilute to the mark. This procedure yields a final concentration of ug/mL, as stated above.

Answer 1

Weigh out 0.05g of the starting material to 0.0002g and transfer it to a 500 mL volumetric flask. Dilute to the mark.

Withdraw 1 mL from the volumetric flask with a volumetric pipet and transfer to a 100mL volumetric flask. Dilute to the mark.

This procedure yields a final concentration of 1.00 ug/mL, as stated above.

Explanation:

As the balance have 0.0002 g sensitivity we can weigh 0.05 g.

If we dissolve 0.05g in 500 mL solvent we will get a concentration of 0.0001 g/mL. Then if we diluted its 1 mL to 100 mL then final concentration will be 0.000001g/mL = 1ug/mL.