Question

Describe, in numbers and with written instructions, how you would prepare 500.0 mL of a 0.125 M KNO3 from a 1.00 M KNO3 stock solution and DI water.

A) Add 500 mL of 1.00 M KNO3 to 500 mL of DI water.

B) Add 625 mL of 1.00 M KNO3 to 375 mL of DI water.

C) Add 200 mL of 1.00 M KNO3 to 300 mL of DI water.

Answer 1

To make a 0.125 M KNO3 solution from a 1.00 M stock solution, measure 62.5 mL of stock solution, then add DI water to reach a final volume of 500.0 mL. Options A, B and C provided are incorrect.

Step-by-step explanation:

To prepare 500.0 mL of a 0.125 M KNO3 solution from a 1.00 M KNO3 stock solution, you'll need to use the dilution formula M1V1 = M2V2, where M1 is the concentration of the stock solution, V1 is the volume of the stock solution you'll use, M2 is the desired concentration, and V2 is the final volume of the diluted solution. Plugging in the known values, we get:

1.00 M × V1 = 0.125 M × 500.0 mL

To solve for V1, you'll rearrange the equation to get:

V1 = (0.125 M × 500.0 mL) / 1.00 M

V1 = 62.5 mL

So, you would measure out 62.5 mL of the 1.00 M KNO3 stock solution and add enough deionized (DI) water to bring the total volume up to 500.0 mL. None of the options given (A, B, C) correctly describe the proper dilution procedure.